What's the difference between be careful about/of/with/in?
Be careful ABOUT what you say to him . (regarding or concerning something)
Be careful of him . He is a bad guy. / Be careful of people who want to cheat you
Bec careful in choosing your friends ./ be careful in China . ok?
The difference > you have to study these 3 word thoroughly to know their various usage . Try the Internet . Its too long to explain here , if I can )