The Acquisition of Swahili Verbal Morphology Abstract
Recently, much attention has focused on the so-called
Root Infinitive(RI) phenomenon, where children in
languages such as German use infinitival verbs in root
context, seemingly optionally. English has been
argued to be an RI language (Wexler 1994), though
English speaking children use bare stems instead of
infinitives. Languages such as Italian, however, have
been shown not to exhibit RIs in early child language. I
present results from a study of Swahili, a Bantu
language with rich agglutinative morphology. Swahili
is an SVO language in which the verbal clause has the
following order of morphemes in an affirmative
indicative sentence: Subject Agreement – Tense/Aspect
– (Object Agreement) – Verb Root – (derivational
Wexler (1994) argues that English children also
suffixes) – Mood Vowel. If we assume that the linear
produce RIs, just like their German, Dutch and French
order of morphemes is a reflection of the hierarchical
counterparts. He shows that although they do not
order of heads (Baker’s (1985) Mirror Principle), then
produce infinitives per se, they produce bare verbs (2),
the morphology of Swahili allows us to test various
which are missing all obligatory inflectional affixes.
theories of the dropping of functional morphemes. The
Wexler argues that these forms are the English
speech of four Swahili speaking children ranging in age
from 1;8 to 3;1 was recorded in Kenya, transcribed in
the CHAT format and coded. The results show that
Swahili children do not produce RIs, but do omit Agr
and T/A markers. Thus the verb may surface with a
Person agreement marker alone, a T/A marker alone, or
neither Person nor T/A. In the latter case the verb
Interestingly, children acquiring Italian (or Spanish or
appears as a bare stem, analogous to what we find in
Catalan) do not to go through this stage (Grinstead
English. These results are discussed in the light of
1998; Guasti 1993/1994). Instead, Italian children, for
various theoretical analyses of RIs, specifically the
example, seem to converge on the adult grammar
Metrical Omission Model (Gerken, 1991), the Small
extremely early with respect to this phenomenon. This
Clause Hypothesis (Radford 1986; Radford 1990),
is surprising since Italian, unlike English, does have a
Rizzi’s (1994) Truncation hypothesis, Wexler’s (1994)
true infinitive. Thus European languages can be
underspecification of tense theory, Hoekstra & Hyams’
classified into two groups: root infinitive languages and
(1998) underspecification of number theory, and
non-root infinitive languages. Root infinitive languages
Schütze & Wexler’s (1996) ATOM model. The basic
can further be divided into true RI languages and bare
clause typology is found to be most compatible with
verb languages. Note that the only well-studied
ATOM, although ATOM fails to account for many of
language that fits into the bare verb category is English.
1. Introduction Root infinitive languages Non-root-infinitive
Children acquiring certain European languages go
through a stage in which they use infinitival verb forms
in root context. This stage, called the Root Infinitive
Stage, or the Optional Infinitive Stage, is characterized
by the optional use of utterances such as the those in
(1). This phenomenon has been heavily studied in several languages, most notably German (1a. and b.,
from Poeppel & Wexler (1993)), Dutch (1c. and d.,
This typology of languages is a problem in our field.
from Weverink (1989)), and French (1e. and f., from
What is the cause of this typology and how do other
languages fit into this typology? Part of the problem is
that relatively little is known about children acquiring
non-European languages. The goal of this paper is to
The verb is embedded within a verbal complex, the
broaden the inventory of languages that is used in
structure of which is given in (6). I will briefly describe
developing acquisition theory, and show that limiting
each element in this complex, except for the optional
our focus to the well-known European languages leads
derivational suffixes, which are not relevant to this
to conclusions which do not truly reflect the constraints
on child language. I will present results from a
longitudinal study of four Swahili speaking children. I
(6) Subject – Tense – Object – Verb–suffixes– Mood
will first outline some important features of Swahili,
and then present results showing how Swahili children
use verbal morphology. I will show how Swahili fits
into the typology in (3), and discuss the difficulties
Subject agreement marks person and number as shown
these data pose for several influential theories of early
in (7), and there are several tense/aspect markers, given
child language : the Metrical Omission Model, the
Small Clause Hypothesis, the Truncation Hypothesis,
the Underspecification of Number Hypothesis, the
Underspecification of Tense Hypothesis, and ATOM
(Agr-Tense Omission Model). I will show that while
the data are most compatible with ATOM, the
complexity of the Swahili data can not be accounted for
(hawa) walianguka 2. Swahili
Swahili is an eastern Bantu language spoken primarily
in Tanzania, Kenya, Uganda and neighboring areas.
The dialect of Swahili in this study is that spoken in and
around Nairobi, the capital of Kenya. It is an SVO
language; the subject and the object may be optionally
null. The verb occurs in a verbal complex which contains inflectional material as well as grammatical
(4) Subject - Verbal complex -
Object agreement also marks person and number, but
unlike Subject Agreement, is optional. The optionality
Most verb roots in Swahili are monosyllabic and
of Object Agreement is dependent on the intended
contain a single vowel, but as the table in (5) shows,
interpretation of the direct object – if the direct object is
other verb root structures are not uncommon. The final
specific, Object Agreement is obligatory, and if the
vowel in the examples in this table are the obligatory
Direct Object is non-specific, Object Agreement is
final vowel in Swahili, without which the verb cannot
obligatorily absent. Because of this optionality and the
surface. Each example has the indicative final vowel.
complications it poses, I will only discuss Subject
Agreement, Tense and Mood in this paper.
Mood is marked as a suffix, and is always the final
vowel in the verbal complex. This final vowel
alternates three ways between the indicative [a], the
subjunctive [e] and the negative [i]. The indicative
final vowel occurs with on-going actions/states, present
habitual actions, past actions/states, future actions/ states, imperatives, etc. The subjunctive is used to
express desires, possibility, necessity, requests, etc.
Primary stress in Swahili is on the penultimate syllable
of any multisyllabic word (Ashton 1947; Maw and Kelly 1975; Myachina 1981; Vitale 1985). Thus in a
disyllabic verb, the stress falls on the first syllable of
the stem, as in (9). Furthermore, secondary stress
usually falls on the subject agreement marker.
Examples are given in (10). (10a) is a transitive
indicative sentence. The subject is Juma and the object
is Mariam, both proper names. The verbal complex
shows 3rd person singular subject agreement with Juma,
contains the past tense ‘li’, and 3 rd person singular
3. The Data
object agreement with Mariam. The verb root ‘fuat’ is
Turning now to the acquisition data, the data collection
followed by the Indicative final vowel ‘a’.
was conducted over a period of 11 months in Nairobi,
Kenya. Biweekly recordings were made of naturalistic
speech in the homes of four children of differing ages.
The data were audio recorded and transcribed using
Juma a – li – m – fuat – a Mariam
CHAT format (MacWhinney & Snow, 1985). Because
Juma SA3sg-past-OA3sg-follow-IND Mariam
of various social and economic difficulties, it was not
possible for all four children to remain in the study for
the duration of the project. The table in (12) provides
the basic descriptive facts about each child.
Tafadhali ni – pat – i – e kalamu
A – na – tak – a ku – fu – a dafu
Because of the complexity of the data and because
naturalistic data is notorious for showing great
fluctuations between individual data points, we pooled
the data in order to stage the children relative to each
other. We did not want to use age as an indicator of
(10)b is a polite request using the subjunctive final
grammatical development as this is unreliable.
vowel. When the subjunctive final vowel is used, quite
Similarly MLU by itself has been noted to have several
expectedly, the tense marker is absent. (10)c is an
drawbacks (see Valian 1991). Therefore a composite
example of a complex sentence, with an embedded
method was used to stage the children, the criteria for
infinitive. Note that the Swahili infinitive marker is a
prefix which occurs in the same position as other tense
markers in tensed clauses. The final example is an
imperative form, which is a bare stem, that is, the verb
b. Verbs/Total Utterances (Valian, 1991)
c. Percent of proto-syntactic place holders
Following Chomsky (1993) and Pollock (1989), and
(Bottari, Cipriani, and Chilosi 1993/1994)
further following Demuth & Gruber (1995) who
analyze Sesotho, a southern Bantu language in a similar
According to these three criteria, four stages were
manner, I assume a structure for Swahili as in (11).
identified, with the files from each child being assigned
The verb raises to Mood, with all else being base
accordingly, shown in (14). Throughout the rest of this
generated in their respective projections2.
paper, for ease of exposition, I will be using this staged
data rather than data from the individual children.
Recall that children in other languages such as English
omit certain obligatory inflectional elements. Given this, we might expect Swahili children to do the same.
Focusing only on the prefixes, and ignoring Object Agreement because of the complications discussed
earlier, there are several logically possible clause types
that Swahili children might produce. These, along with
Examples of each clause type are given in (17).
my terminology for them, are listed in (16).
Example (a) is a full clause which is adult-like and fully
grammatical. Example (b) is a [-SA] clause, that is, it is
missing the subject agreement marker, but has a tense
marker, in this case a future tense marker. Example (c)
is a [-T] clause, that is, it is missing a tense marker, but
has subject agreement. Example (d) is a bare stem
missing all prefixes, and example (e) is an RI.
(15)a. is a full clause, which contains both Subject
Agreement and T. (15)b. is a [-SA] clause, containing
tense, but missing subject agreement. (15)c. is a [-T]
clause containing Subject Agreement but missing tense,
and (15)d. is a bare stem, which is missing all prefixes.
Let me be clear here on a terminological point: the term
‘bare stem’ is used to refer to a verb root plus an
indicative final vowel. Other prefix-less verbs also
occur in child (and adult) Swahili, namely subjunctive
clauses. These are not discussed in this paper3,
although see Deen & Hyams (2001) for details on
subjunctive use in Swahili child language.
Additionally, it should be noted that bare stems in
Swahili are different from bare verbs in English, the
latter showing a total absence of inflection, while the
former show mood marking. Returning to the possible
clause types in (15), putting aside theories of
agreement, root infinitives, and theories of infinitives
for the moment, and given that Swahili has an infinitive
morpheme, root infinitives should be possible in child
The verbal utterances in the Swahili corpora were
(MacWhinney & Snow, 1985), excluding imperatives,
imitations, repetitions and non-indicative utterances.
The results are presented in (16). Interestingly, all five
(although, the child could have intended ‘I want to
possible clause types are attested, although in varying
Note that while RIs are attested, they are exceedingly
rare (16/1342 = 1%). In fact, the rate of RIs in Swahili
is even lower than that reported for languages such as
Italian (for which some report rates as high as 16%,
So the errors that we see in child Swahili are errors of
e.g., Guasti (1993/1994); see Sano (1995) for a review
omission, not errors of commission. This is entirely in
of proportions of nonfinite clauses in various
line with what we know of other languages.
languages). This lack of use of the infinitive cannot be
attributed to the fact that the Swahili infinitive is a
These results are intriguing in many respects. They
prefix (as opposed to a suffix) because other
show a clear developmental trend in the use of the
inflectional prefixes are used. Thus, with respect to the
inflectional prefixes in Swahili, the likes of which we
typology of languages in (3), Swahili falls into the
have not seen in any language studied thus far. There
same category as English: it is a bare verb language,
have been several theories accounting for children’s
not a true RI language. Swahili provides us with
omission of inflectional material and use of RIs, mostly
another example of a bare verb language, making
based on languages which lack independent marking of
English no longer unique in this respect. As for the
SA and T. I will now use this Swahili data to evaluate
remaining four clause types, I have plotted their various
proportions in a line graph, given in (18).
The first is a metrical model of omission, first proposed
We see from (18) that in stage 1, all four clause types
by Gerken (1991), and later developed in Gerken &
are produced at or above 18%. [-SA] clauses and bare
McIntosh (1993) and adapted for Sesotho by Demuth
stems are more frequent than [-T] or full clauses, but
(1994). Gerken found that English children are more
not significantly so. In stage 2, [-SA] clauses increase,
likely to omit weak unstressed syllables in iambic feet
as do full clauses, but bare stems and [-T] clauses
as in (19), or weak unstressed syllables preceding
decrease significantly. In fact, by stage 2, [-T] clauses
trochaic feet (as in 20), but not the weak unstressed
occur at a rate of less than 10%. By stage 3, full
syllables within trochaic feet (as in 21).
clauses become the most prevalent form, followed by [-
SA] clauses. Bare stems fall below the 10% mark, as [-
T] clauses drop to 5%. This trend continues in stage 4,
with the relevant proportions approaching adult norms. Subject to drop The only significant difference between adults and
children in stage 4 is the proportion of [-SA] clauses,
which is almost 30%. This points to a very clear
difference in the grammar of Swahili children between
[-SA] clauses on the one hand and [-T] and bare stems
on the other. The latter clause types cease to be a
possibility relatively early and fade out rather rapidly,
while [-SA] clauses remain a possibility even into stage
This, she claims, accounts for the omission of
determiners and other unstressed functional material in English. Demuth (1994) applies this theory to the
omission of noun class marking in Sesotho, and
suggests that it may also explain the omission of verbal
prefixes. However, the Swahili data are incompatible
with a simple metrical model. Recall that stress in the
Swahili verbal complex is always on the penultimate
syllable, and secondary stress in the verbal complex
usually falls on the subject agreement marker. Taking
a leftward parsing of the string produces a trochaic foot
It should be noted that while subject agreement and
on the right edge containing the verb and the mood final
tense are used optionally, when they are used errors are
vowel. Since most verb stems in Swahili are disyllabic,
extremely rare. In all the verbal utterances included in
this is the most common pattern. Furthermore, the
(16), there were a total of 9/1342 errors: less than 1%.
Subject Agreement and Tense prefixes are analyzed
together as a trochaic foot , yielding two trochaic feet.
others. Such a hypothesis claims that the adult axiom
According to the Metrical Model, in cases such as (22)
of CP=root has not developed in young children, and so
when the verb stem is disyllabic there should be no
they can optionally choose to specify the root as some
omission. If we now consider trisyllabic verb stems
lower projection in the tree. When AgrOP, for
example, is specified as the root, then everything above
AgrOP is omitted, and if TP is specified as the root,
everything above TP is omitted. This theory predicts
that nothing from the middle portion of the tree will be
omitted. For Swahili it predicts that children may
produce full clauses (that is, no truncation because the
we see that the rightmost trochaic foot includes the
root is CP or AgrSP), they may produce [-SA] clauses
second syllable of the verb stem and the mood final
(when the root is TP), they may produce Bare stems
vowel. The first syllable on the verb stem forms
(when the root is either AgrOP or MoodP), or they may
extrametrical information, and so should be subject to
produce Bare Verb Roots (when the root is VP).
omission. However, crucially, the subject agreement
and tense markers form a trochaic foot, and should not
(24) Predictions of Truncation for Swahili:
The vast majority of verbs produced by the children in
this corpus were disyllabic or trisyllabic, and so a
metrical account falls short of explaining the omissions.
Furthermore, children tend to center on the verb stem
and produce the verb stem correctly, irrespective of
As mentioned earlier, verbs missing the final mood
syllabic structure5. What they seem to have problems
vowel are unattested in child Swahili, and so (24) d is
with more than anything are the inflectional prefixes.
problematic for truncation. This could be accounted for
Metrical theory cannot account for this specific
by postulating a lower limit to truncation, although no
such proposal exists for any other language that I am
Several researchers (such as Radford (1986), Lebeaux
aware of. However, a much more serious problem for
(1988); Guilfoyle & Noonan (1988), etc.) looking
truncation is the [-T] clauses. These are problematic
mostly at English speaking children’s bare verbs and
because they contain material from low in the tree and
omission of determiners have proposed that very young
material from high in the tree, but are missing material
children lack functional structure entirely. Given the
from the middle portion of the tree – precisely what
Swahili structure in (11),we expect Swahili speaking
children to produce no prefixes and no mood final
In addition to these theories, there have been several
vowel. However, interestingly, Swahili children never
theories of underspecification which attempt to account
omit the final mood vowel. Furthermore, from the
for RIs. One such theory was proposed by Hoekstra &
earliest stages they use the final vowel appropriately.
Hyams (1998), in which they propose that only number
This dichotomy between Subject Agreement and Tense
is optionally underspecified in the grammars of young
on the one hand and Mood on the other is evidence
children. With number underspecified, children
which a No Functional Structure Hypothesis simply
acquiring number-marking languages such as Dutch or
cannot accommodate. Furthermore, such a hypothesis
English use an infinitival form or a bare stem
does not account for the differential omissions of the
respectively. Languages such as Italian are person
marking languages, and so do not exhibit RIs or bare
Similarly, a theory that claims a single functional
verbs. According to their definitions, Swahili is a
projection above VP, such as that proposed by Clahsen
person marking language, and so an underspecification
et al.(1996) in which there is a single unitary
of Number theory predicts that Swahili children should
inflectional projection which later splits into two or
not omit any functional elements. This is clearly not
more projections, predicts that Swahili children should
use one and only one prefix at any one time. However,
A second underspecification theory is that proposed by
as we saw in (18), Swahili children produce full clauses
Wexler (1994), in which tense is underspecified.
which contain both Subject Agreement and T.
However, such a theory predicts that only tense should
Furthermore, they produce bare stems, which contain
be omitted, while we see that in Swahili agreement is
neither Subject Agreement nor T. This is not predicted
The final underspecification theory I will consider is
Let us turn now to a Truncation-type hypothesis such as
proposed by Schütze & Wexler(1996) and in more
that proposed by Rizzi (1994), and subsequently by
detail in Schütze (1997). They claim that children can
optionally omit either Agr, tense, both or neither. This
difference from other inflectional heads. This
model, called ATOM (Agr-Tense Omission Model)
interesting fact will be the focus of Deen & Hyams
predicts that Swahili children may produce full clauses,
[-SA] clauses, [-T] clauses and bare stems, as shown in
One conclusion we can draw from this study is that our
previous understanding of the typologies in child
language were overly simplistic and based on languages
that confounded various inflectional properties.
Languages like Swahili that mark inflectional heads
distinctly can be enormously useful in our
understanding of the development of child grammar
and how inflection is used in their grammars.
ATOM appears to make the correct predictions with
respect to the various possible clause types, but several
questions remain. For example, how does this model
My deepest thanks go to Nina Hyams, without whom
account for the differing proportions of the four clause
none of this would have surfaced in the form that it did.
types? Specifically, what accounts for the difference
Thanks also to Carson Schütze, for long and detailed
between [-SA] clauses on the one hand and [-T] clauses
discussions and comments; the UCLA Psychobabble
and bare stems on the other? Secondly, Swahili
group for their comments and discussion, and
children have shown that they do underspecify Agr and
Dominique Sportiche for his help and insight into the
T, and Swahili does have an infinitive marker, but why
syntax of Swahili and Bantu languages. Of course, all
do Swahili children produce bare verbs like English
children and not root infinitives like German children?
Finally, since Swahili is a null subject language which
has rich person agreement, why does it not pattern like
1 The paradigm given in the text is for animate (usually of
Italian? ATOM does not answer these questions, and
classes 1 and 2) nouns. SA in Standard Swahili is somewhat
so while the basic range in clause types is predicted, the
more complicated in that it has a distinct SA system for each
noun class. Nairobi Swahili, on the other hand, has a reduced SA marking system for inanimate nouns. The simplified view
I have presented in the text is to avoid this complication, as it
has no bearing on the issues in this paper. See Deen
Unlike other European languages which either mark
just one inflectional property, or conflate several
2 This is the structure and analysis that Demuth & Gruber
properties into a single head, Swahili marks Subject
(1995) propose for Sesotho. While such an analysis raises
Agreement and Tense individually on independent
certain problems with the licensing of inflectional elements, I
morphological heads. Because of this characteristic,
will continue to assume it for the purposes of this paper. For
Swahili offers us a new window into child language,
a more detailed analysis of Swahili, see Deen (1999) and
revealing several interesting facts. First, we see that
Deen (forthcoming), chapter 2. See also Ngonyani (1996) for evidence of verb raising and the positioning of Mood in
children may optionally and independently omit Subject
Agreement and Tense. Secondly, when inflectional
3 The subjunctive occurs with a SA marker, but does not
material is used, it is overwhelmingly used correctly.
occur with T. Therefore, these clauses differ from [-T]
This is not surprising, as this is a hallmark of child
clauses only in the final vowel. Methodologically, these pose
language. Third, RIs are unattested. This is somewhat
a problem if we are trying to ascertain the nature of [-T]
surprising since Swahili does have an infinitive marker.
clauses, since it is possible that children are producing
One possible reason for this is that Swahili, like
subjunctive forms with an incorrect final vowel. Apart from
English, marks the infinitive as a prefix, and perhaps
the fact that such errors of commission are extremely rare in
the position of the infinitive leads to a dropping of the
child language in general, these clause types are very clearly distinguishable on the basis of context. Subjunctives very
infinitive prefix. However, since other inflectional
clearly indicate an irrealis-type meaning, while presumably,
prefixes are used in varying proportions, why would the
the [-T] forms should not since they are marked indicative.
infinitive be completely absent if Swahili were indeed
This interpretive difference was used as a criterion in
counting, with all those utterances that could possibly be
Furthermore, despite Swahili being a pro-drop language
considered a subjunctive (due to their irrealis interpretation)
with rich person agreement, bare verbal stems still
occur. This is surprising given what we know about
A possible objection is that other parses are possible.
Italian and Spanish, where such verb forms do not
However, there are two conditions which rule out other
occur. Finally, the mood final vowel is used correctly
significantly different parses. First, every foot must contain one and only one strong syllable, limiting the string in (23) to
without omission from the earliest stages, a marked
two feet. The first strong syllable (left-most) can only be
Gerken, LouAnn, and B. McIntosh. 1993. The interplay of
parsed as trochaic, while the second foot can be parsed as
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Traveller’s Diarrhea This fact sheet provides basic information only. It must not take the place of medical advice, diagnosis or treatment. Always talk to a healthcare professional about any health concerns you have, and before you make any changes to your diet, lifestyle or treatment. What is traveller's diarrhea? Traveller's diarrhea is frequent, loose, or watery bowel movements resulti
OSTEONECROSIS OF THE JAW Overview Reports of bisphosphonate-associated osteonecrosis of the jaw (BON) associated with the use of Zometa (zolendronic acid) and Aredia (pamidronate) began to surface in 2003. The majority of reported cases have been associated with dental procedures such as tooth extraction; however, less commonly BON appears to occur spontaneously in patients taking thes