I want to know___his homework yesterday evening.A:if he finished B:whether he had finished
题目
I want to know___his homework yesterday evening.A:if he finished B:whether he had finished
为什么
答案
B 过去的完成时呀.
这里不是虚拟语气,所以不要跟虚拟语气的完成时和过去式弄混了.
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
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