Ben did his homework after school yesterday.(改为否定句)Ben ---- -------- his homework after school yesterday.

问题描述:

Ben did his homework after school yesterday.(改为否定句)
Ben ---- -------- his homework after school yesterday.

Ben 【didn't】【do】 his homework after school yesterday.
助动词后用动词原形,主动词本身变成过去时态的否定形式