Question

It isn’t clear_____ is to blame.We need to find a solution to the problem first.

A．who is it that

B．who it is that

C．it is who that

D．that who it is

Answer 1

B

试题分析：这里It是形式主语，who引导的是真正的主语从句，从句是强调句型，被强调部分是who，因为who是连词必须放在主语从句的句首，又因为主语从句的语序是陈述语气。故选B。温馨提醒：强调句型的结构：it be 被强调部分+ that+其他，判断强调句型的方法是把it be that去掉，整个句子是成立的。
点评：把主语从句与强调句型放在一起考查，增加了试题的难度，考生必须这两个知识点都能熟练掌握才行，近几年高考单选考查多个知识点的频率高了。
即学即练：_____  you usually go to work?
A. How is it that     B. How it is that       C.it is how that        D.that how it is
解析：A. 句意：你通常是怎样去上班的？