6Chapman,RS,Seung HK,Schwartz SE,Kay-Raining Bird E.Language skills of children and adolescents with Down SyndromeⅡ:Production Deficits. Journal of Speech and Hearing Research . 1998
7Fabbretti,D,Pizzuto,E,Vicari,S,Volterra,V.A story description task in children with Down’s syndrome:lexical and morphosyntactic abilities. Journal of Intel-lectual Disability Research . 1997
8Fowler A,Gelman R,Gleitman L.The course of language learning in children with Down syndrome:longitudinal and language level comparisons with young normally developing children. Constraints on Ian-guage acquisition:studies of atypical children . 1994
9Mervis CB.Williams syndrome:15years of psychological research. Developmental Neuropsychology . 2003
10Perovic A,Wexler K.Complex grammar in Williams syn-drome. Clinical Linguistics&Phonetics . 2007
