Iwas(athome)lastweek.括号代替划线部分为什么Be动词要用Were，而不用was？

Question

I was (at home) last week.括号代替划线部分
为什么Be动词要用Were，而不用was？

Answer 1

was 是is 和am 的过去式.
were 是are 的过去式.
就括号提问：Where were you last week.
I am 过去就是 I was
You are 过去式就是you were
所以就用were 了.
提问的时候不能说：Where was I last week 自己当然知道自己在哪里了.所以提问时,I也改为You了.