Question

Not until he had left his friend _______ how important friendship was for him.

1. A.
   did he realize
2. B.
   he realized
3. C.
   had he realized
4. D.
   he had realized

Answer 1

A
试题分析： 1.当Not until位于句首时,句子要倒装。其结构为:Not until+从句/表时间的词+助动词+(主句)主语+谓语+...。故排除BD，realize发生在had left 之后，故用一般过去时。 ②Not until next week will the sports meet be held.直到下周才开运动会。
考点：部分倒装。
点评：当Not until位于句首时,句子要倒装。
即学即练： It ______ we had stayed together for a couple of weeks ______ I found we had a lot in common.
A. was until; when B. was until; that C. wasn’t until; when D. wasn’t until; that
选D