Not until he left his home to know how important the family was for him.
A. did he begin
B. had he begun
C. that he began
D. he had begun
网友回答
(答案→)A. did he begin
B. had he begun
C. that he began
D. he had begun
解析：
试题分析:考查倒装句。Not until +从句位于句首时从句需用部分倒装语序，即一般疑问句语序。所以排除C、D选项，而根据时间状语从句until he left his home 可以判断主句应该用一般过去时，故A选项正确。
句意：直到离开家他才开始知道家庭对他来说是多么的重要。