In English the nonfinite form is simply a bare verb, but in languages with a morphological distinction it usually takes the form of an infinitive. During the relevant stage the child, unlike an adult, sometimes uses an infinitive as the main verb of a root clause. Luigi Rizzi and certain other researchers therefore favor the term "root…

Passives has been the focus of much research in language acquisition since the 1970s. It has been clear from this research that young children seldom produce passives spontaneously, particularly "long" or "full" passives with a by-phrase; and they usually perform poorly on experimental tests of the comprehension of passives, especially passives of…