My English teacher has been to Greece and Spain.(对两个国家提问)

问题描述:

My English teacher has been to Greece and Spain.(对两个国家提问)
为什么一定要用which country而不能用what countries?
everyone是单数还是复数?

which country的意思是:哪一个城市
而what countries的意思是:什么城市
提问的话当然是哪一个城市喽
everyone是单数