e careful about/of/with sth或者be careful about/in+doing sth皆为：小心,当心,警惕的意思
be careful with glasses小心玻璃杯
be careful of the dog,it sometimes bites people留心那条狗,有时候咬人
be careful about/of what you say to him对他说话可得小心
be careful about/in crossing the road过马路要留神
he is very careful with his money他用钱很仔细