Not until the meeting was over ____ that he had made a mistake in his speech

问题描述:

Not until the meeting was over ____ that he had made a mistake in his speech
A he realized B did he realize C he has realized D has he realized
为什么选b?

因为not until开头
句子要用倒装
排除A C
D的话因为后面用had made
所以整个句子要用过去式
所以选B