can have done could have done should have done should to do shouldn't have done shouldn't to do还有needn't have doneneedn't domustn't have donemay not have donemight not have done
问题描述:
can have done could have done should have done should to do shouldn't have done shouldn't to do
还有
needn't have done
needn't do
mustn't have done
may not have done
might not have done
答