what caused the accident and who was responsible for it ( ) a mystery to us.
问题描述：
what caused the accident and who was responsible for it ( ) a mystery to us.
A.remain B.remains
如果是的话,为什么后面是a mystery?
答
动词的单复数是跟前面的主语有关的,答案是A的话,前面两件事情的肇事者显然不是同一种东西,前者是原因,后者是人,因此在这里最好不把这两件事情当作一个整体,而是当作两个事情,如果句子是Who caused the accident and was responsible for的话,选择B就好一点.这么说你可能容易接受一点,He（假设是造成事故的原因）and she（假设是需要对时间负责的人）（）a mystery to us,你会选择什么?（最后关于你说的a mystery讲讲,举个例子,They make a cake
./We became（are） a team.仔细想想你说的宾语或者表语单复数对动词单复数是否有影响）噢，我知道了！谢谢！