问题
选择题
It was only after she had read the papers _______ Mary realized the homework before her was extremely difficult to complete.
A．when
B．that
C．which
D．what
答案
答案：B
题目分析：句意：就是在玛丽读了文章之后，她才意识到她面前的家庭作业非常的难完成。这个句子中含有It was，首先要考虑它是不是一个强调句，把It was和横线去掉，这个句子仍然结构完整，语义清楚，所以说这个句子就是一个强调句，选B。