题目内容：

----he passes the exam,his father will take him to Beijing for a visit makes him work very hard
A IF,B THAT IF,C THAT,D IF THAT 急

优质解答

B
that 引导主语从句his father will take him to Beijing for a visit ,做makes him work very hard的主语；而这个主语从句中又含有一个条件状语从句if he passes the exam.