is过去式是was，它是一个动词，是be动词的一种，意思为“是、存在”。常放在其他词后，缩写为's，造句：This is a book.这是一本书。

is过去式例句：

1、I was astounded by its beauty.

它的美丽震撼了我。

2、I was waiting for a bus.

我在等公共汽车。

3、It was great to begin with but now it's difficult.

一开始非常好，但现在可就难了。