Copyright © American Speech-Language-Hearing Association From: Surface Forms and Grammatical Functions:  Past Tense and Passive Participle Use by Children With Specific Language Impairment J Speech Lang Hear Res. 2003;46(1):43-55. doi:10.1044/1092-4388(2003/004) Legend: Mean percentages correct (and standard errors) for the use of past tense -ed and passive participle -ed by the children with specific language impairment (SLI), the normally developing children matched for mean length of utterance (ND-MLU), and the normally developing children matched for age (ND-A). Date of download: 11/3/2017 Copyright © American Speech-Language-Hearing Association