isnt的完整形式：is not。is not（完全式）=isnt（缩写式）

释义：(is not 的常用口语形式)不是

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？