Spelling. These are just dumb little things to look for. Did you spell all the identifiers the way you think you did. The problem is, when you read code you see what you expect to see.

拼写错误，你可能得找找这些粗心的小错误,你是否拼对了标识符,问题是当你阅读代码的时候,你看到的都是你以为的。

麻省理工公开课 - 计算机科学及编程导论课程节选

Just when you think you know all Central Park,

当你自以为你了解中央公园的一切的时候，

最美丽的公园 - SpeakingMax英语口语达人