1、使用对象不一样
be careful of 一般是指对某样东西……小心
be careful about 通常是对某件事（人）小心
2、语气色彩不一样
Be careful of强调对...认真，细心，小心（比较褒义）
Be careful about强调的是要当心、小心，对..提高警惕（中性词）
3、词义广泛性不一样
be careful of 当心；注意；当心…对…仔细
例句：
1.You've got to be careful of these Eastern lawyers. If you are not careful, they'lltake you and turn you inside out.
对这些东部的律师可得提防。一不小心，他们就会抓着你，把你整得够呛！
2.It's easy to think you will forget anyway, be careful of that thought.
如果你总是想着“我反正都会忘记的。”那就要小心了。
Be careful about 关切；谨慎对待；重视
例句：
1.This forces these two dependent projects to be very focused on realistic status,as well as be careful about assigning new activities.
这就迫使这两个相互依存的项目集中关注现实的状况，同时对分配新的活动也会十分小心仔细。
2."He loves to drink, so I once told him to be careful about his drinking, " Yoshio Mori, a former prime minister, said in a TV interview.
“他喜欢喝酒，所以我曾告诉他要对喝酒多加小心。”前首相森西朗在一个电视采访中如是说。
跳蚤的华丽转身
