问题补充：
It was it raised so many difficult questions the book took a long time to come out.
A. that; that
B. since; which
C. because; that
D. because; which
答案：
A. that; that
B. since; which
(答案→)C. because; that
D. because; which
解析：考查强调句：强调句的结构是：It is/was+强调部分+that+其余部分，判断是否是强调句的方法是：去掉it is/was+that…句子还能完整，就是强调句，如果把it is/was+that…去掉，这句话变成the book took a long time to come out. it raised so many difficult questions句意：这本书很长时间才出版，因为它引发了很多问题。选C.
