题目内容：

When and where to hold the meeting _ still unknown to us.A.are B.were C.is D.was
When and where to hold the meeting _ still unknown to us.
A.are B.were C.is D.was
为什么是C

优质解答

When and where to hold the meeting _ still unknown to us.
A.are B.were C.is D.was
选项是C.
因为主语是【一个】不定式短语,表单数.
句意是：“在什么时候在什么地方举行这个会议,我们还不知道”.