Not until he left home to know important the family was for him.A. did he begin; whatB.

问题补充：

Not until he left home to know important the family was for him.

A. did he begin; what

B. had he begin; how

C. did he begin; how

D. had he begin; what

答案：

A. did he begin; what

B. had he begin; how

(答案→)C. did he begin; how

D. had he begin; what

解析：本题考查倒装和从句。句意：直到离开家，他才开始意识到这个家对他来说是何等的重要。：not until引导的从句置于句首时，主句需用部分倒装。主从句的动作基本同时发生，故用一般过去时。第二个空所选之词修饰important，故用how。