isn't的完整形式：is not。is not（完全式）=isn't（缩写式）。

isn't（缩写式）= is not（完全式）

isn't

英[ˈɪznt]，美[ˈɪzənt]

例句

1、It isn't too difficult once you get the idea

你一旦弄懂了，就不太难了。

2、Perhaps he isn't coming.

他许不来了。

3、It's past the appointed time. Maybe he isn't coming.

约定的时间都过了，别是他不来了吧？

4、He is not my brother.=He isn't my brother.