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”。它的美式读法是[ɪz]，英式读法是[ɪz]，常放在其他词后缩写为 's，造句：This is a book.（这是一本书）。
is基本含义
be 的第三人称单数现在时形式，常放在其他词后缩写为-’s;
[例句]This is the one major drawback of the new system.
这是新系统的一大弊端。
过去式：was
was双语例句
The system was state of the art.
这一系统是当时最先进的。
It was a time of peak demand for the product.
那是对该产品需求最旺的时期。
Much of the form was not applicable to me.
表格中很多部分不适用于我。
For a long time his death was concealed from her.
他的死瞒了很长时间都没告诉她。
She was not only intelligent but also very musical.
她不仅聪明，而且极具音乐天分。