be careful of …
注意,小心......后接名词,
动名词或从句.
Please be careful of your spelling.
Be careful of what they have said.
be careful with…
小心……
[句型解析]
嘱咐别人小心做事, 我们可以用上“Be careful with...”，“with”后接名词或动名词。也可以说“Be careful (not) to do...”或“Be careful that you don’t...”。
Be careful abou强调的是要当心、小心，对..提高警惕
例句: Everyone should be careful with fire when using it. 每个人都应该谨慎用火
Be careful in用法和be careful with用法近似
Be careful of强调对...认真，细心，小心（比较褒义）
例句：You are very careful of your work.你对你的工作很谨慎/认真
It is really careful of you 你很认真（褒义）