通常理解isn't为否定的意思或“不是”。isn't=is not，是is not的用法和缩写经常用在反义疑问句里，反义疑问句起强调作用，没有不礼貌的问题。
双语例句
1.It isn't too difficult once you get the idea.
你一旦弄懂了，就不太难了。
2.'That's crazy,' I said. 'Isn't it just?' he said.
“那简直是疯了，”我说。“谁说不是呢？”他说。
3.Perhaps he isn't coming.
他许不来了。
4.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？
5.Isn't that enough for you?
那对你来说不够吗？
