careful

1.He is careful in reading every sentence是“他细心地读每句。”He is careful to read every sentence是“他留心着一定要读每句（一句也不肯遗漏）。”He is careful enough to read every sentence是“他这样地留心，所以每句都读（一句也不遗漏）”。

2.careful后面往往接of。例如：You ought to be careful of your spelling.假使后面接以how, where等词引导的从句，便不用of，如You ought to be careful how you spell和She is always careful where to use a comma and where to use a semicolon。

3.Be careful (that) you don't catch cold里的that可有可无。

4.可以说Be careful of your pronunciation，不可说Be careful of your mis pronunciation。

5.She is always careful what she does是“她时常当心她做什么（避免做不该做的事）”。She is always careful in what she does是“对于她做的事，她时常小心去做”。She is always careful of what she does可能有上面两句中任何一句的意思。