1、was和were都是过去时。was是is和am的一般过去式，were是are的一般过去式。2、was与I/He/She/It连用，were与We/They/You连用。
1.was用于I,he,she,it以及单个人作主语的句子。
例如：
I was born in 1998.
He was a doctor three years ago.
She was at home yesterday.
It was Monday yesterday.
Mike wasn't at home this morning.
2.were用于you,they,we以及两个以上的人作主语的句子。
例如：
You were at home yesterday.
They were at the playground an hour ago.
We were singing in the room an hour ago.