what____you____(buy) yesterday 这里如何填空?
what____you____(buy) yesterday 我见有人填为what did you buy yesterday 这个句子是一般过去时,为啥后面的buy不改为bought?还是只是他回答错了?这个句子正确的应该为what did you bought yesterday?
为啥是did buy呢？没弄明白…… 可以举几个例子吗?