It ____ Jack and Mary who helped me the other day.为什么是was,而不是were?

问题描述:

It ____ Jack and Mary who helped me the other day.
为什么是was,而不是were?

WAS

因为形式主语 it 是单数的

强调句型,固定的
如果是现在时态就是
It is 强调部分 that 句子剩余部分
如果是过去时态就是
It was 强调部分 that 句子剩余部分