A research on the nature of second language (L2) acquisition by adult learners has investigated the relationship between knowledge of functional categories and their abstract features, and knowledge of their morphological realization. Functional categories, such as Det(erminer), Infl(ection), and Comp(lementizer), are categories whose members have a grammatical function, such as complementizers, auxiliaries, tense and agreement markers, and determiners. Research on adult L2 French acquisition so far favors nonimpairment approaches to L2 acquisition. Prévost analyzed longitudinal data from four adult learners who had just started learning French at the time of their first interview. Prevost and White also investigated verbal agreement, as well as agreement between a clitic and its DP referent in clitic doubling constructions. The predictions of the Impaired Representation Hypothesis were not confirmed by the data. The fact that finite verbs are almost always placed to the left of negation cannot support either the global or local view of that approach.