如何解释英文单词are的过去式？ are were的关系是什么？

1、are的过去式是were，是be动词

2、We wre cousins.我们是表亲

3、Jim and I are getting married.我和Jim要结婚了

4、We were all badly bitten by mosquitoes.我们都被蚊子咬惨了?