He must have done his homework last night,didn't he? 这里为什么用didn't而不用haven't?
问题描述：
He must have done his homework last night,didn't he? 这里为什么用didn't而不用haven't?
错了 是 hasn't
答
must have done 的结构,前句强调对过去情况的猜测时（一般有过去时间状语）附加部分用 didn’t + 主语.如果前句强调动作的完成,附加部分则用 haven’t (hasn’t ) + 主语.He must have met her yesterday,didn’t he...