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

用单数，如：
The house where is near to the lake is my family.
其中，第一个is是where引导的从句的谓语动词，第二个is是整个主句的卫浴动词。

从句作主语，谓语用单数

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.

when and where the factory will be built has been decided.单数