when and where 引导的主语从句谓语动词用单数还是复数

题目

when and where 引导的主语从句谓语动词用单数还是复数
那如果是表语从句呢？
eg：the guestion ____(is /are) when and where they live

答案

is
如果when和where连在一起用单数,如果分开用复数,例如：
When and where they had the party was unknown.
When they had the party and where they had it were unknown.