be careful的各种搭配：
careful后跟about
be careful about sth讲究，小心，当心；慎重的，注意...的；对...小心
be careful about doing sth 慎重、小心、当心做某事
careful后跟of
be careful of sth爱护、关切、挂念、呵护；当心、留意、注意
be careful of the traffic. 注意交通安全。
be careful of/as to wh-从句（of在后接wh-从句时常省略）
careful后跟with
be careful with 小心处理；对…谨慎 ；节俭的`、节省的
be careful with the/your money花钱精打细算；吝啬、小气
be careful with小心火
careful for关心、惦记
careful in...在...方面、过程中小心、注意
