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?