在谈论过去的地点、事件、事物和人时，be动词就要使用过去式：was或者were。
was是is和am的过去式，were是are过去式，使用的时候要注意主谓一致。
例如：
It was a sunny day yesterday. 昨天天气晴朗。
They were too busy to go shopping. 他们太忙，以至于没空去购物。
was和were的否定可以直接在后面加上not，变成wasn't (was not)或者weren't (were not).
比如：
I wasn't in town last week. 上周我不在城里。
They weren't ready to get married then. 他们那时没准备好结婚。
例句:
He was not in London at that time.
他那时不在伦敦。
We were late for the exam last week.
我们上周考试迟到了。
It was a great time seeing him again.
再次见到他很开心。