Only when he had handed in his exam paper did he realize he had made several mistakes.
题目
Only when he had handed in his exam paper did he realize he had made several mistakes.
为什么不用has he realized
has he realized 和did he realize的区别
答案
he had handed 过去完成时态的使用就是要退两步,简单说,在一般过去时态的基础上再向前退一步,现在完成时态属于现在时态范畴,不能直接退到过去完成啊
举一反三
已知函数f（x）=x，g（x）=alnx，a∈R．若曲线y=f（x）与曲线y=g（x）相交，且在交点处有相同的切线，求a的值和该切线方程．
我想写一篇关于奥巴马的演讲的文章,写哪一篇好呢?为什么好
最新试题
热门考点