这道题选D that,这是强调句,它们的区别是
强调句that是一个不完整的句子.因为句中被强调的部分已放在了前面.而主语从句that之后是一个完整的句子.如
It is an honour that I have been invited to the ball.这句是主语从句
It is a book that I bought on my way home yesterday.这句是强调句,再有主语从句的主句除有名词作表语外还可有形容词,过去分词等.而强调句没有.因为强调句不对形容词强调.
如下面这两句都是主语从句.
It is said that Tom is writing a book.
It is clear that he is satisfied with my work.