troubles me most right now is I can’t remember where I have put my car keys.A. That ;what

问题补充：

troubles me most right now is I can’t remember where I have put my car keys.

A. That ;what

B. What;that

C. What;what

D. That;that

答案：

A. That ;what

(答案→)B. What;that

C. What;what

D. That;that

解析：考查主语从句及表语从句。第一空是主语从句，从句中缺少主语，故用What，第二空是由that,引导的表语从句，句意：现在使我最麻烦的就是我不能记起我把车钥匙放哪里了。所以选B。