---It is he often fails in the exams makes his parents worried about him.---So he

问题补充：

------ It is he often fails in the exams makes his parents worried about him.

------ So, he has to work whole- heartedly.

A. what; that

B. that; what

C. that; that

D. / ; that

答案：

A. what; that

B. that; what

(答案→)C. that; that

D. / ; that

解析：考查强调句型和主语从句。从结构可知第一个空是主语从句，句子意思完整不缺少成分，所以用that引导，而第二个空根据特点判断是强调句型，即把it is …that去掉句子完整，句意：---他经常考试不及格让他父母对他很担心。--这么看来，他得全力投入学习了。