It is he often fails in exam makes his parents worried about him.
A. because, that
B. that, that
C. 不填, that
D. what, that
网友回答
A. because, that
(答案→)B. that, that
C. 不填, that
D. what, that
解析：考查主语从句和强调句型。整个句子是强调句型，所以第二空用that引导；去掉it is…that,剩下 he often fails in exam makes his parents worried about him.
可知 he often fails in exam是主语从句，且从句不缺成分，所以用that引导。选B。