Mary__her homework last night but she can't find it now Adoes finish B.did finish C did finished
问题描述：
Mary__her homework last night but she can't find it now Adoes finish B.did finish C did finished
答
B
did用在肯定句中表示“确实，的确”的意思，因为助动词后要用动词原形，所以选B
答
选b
遵循一次变形原则 前面助动词已变形为过去 后面就不可在变了 用原型。
答
B强调
答
B did finish
did 表强调
玛丽昨晚的确是做完作业了，但是现在却找不到
答
选择C.
did是强调用法,句子是一般过去时,finish要用过去式.