It is he often fails in exams makes his parents worried about him.
A. what; that
B. that; what
C. that; that
D. /; that
网友回答
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。强调句型it is/was... that去掉后不影响句意，据此排除B；根据makes可知，that he often fails in exams是主语从句，he often fails in exams是主谓结构，不缺少成分，排除what；that引导主语从句时不能省略，排除D；故选C。