The single most important factor contributes to success is you do every single day．A. th

问题补充：

The single most important factor contributes to success is you do every single day．

A. that; that

B. which; what

C. which; what

D. that; what

答案：

A. that; that

B. which; what

C. which; what

D. that; what

解析：从句子结构分析,第一个空考查定语从句的关系词,因先行词前有形容词最高级修饰且指事物故只用that引导;第二个空跟在be动词后,表明是一个表语从句,用do后缺少宾语,因此只能由what来引导。