题目内容：

8.Could __ have been ____ who helped Sunny get her work done?
A.they ,it
B.they ,them
C.it,them
D.it,they
为什么不是其他选项?尤其是C?

优质解答

改为肯定句为 It could have been they who helped Sunny get her work done.是强调句.如果该成It was they who helped Sunny get her work done.应该可以看出来了吧!(去掉强调的It was...that...应为一个完整的句子...