1.be careful of:小心,当心,留神,注意。例如:
例70:The public were warned to be careful of rats. (公众被警告要当心老鼠。)
2.be careful with:细心,注意。指细心地处理或对付某人或某事。例如:
例71:You’d better be careful with your work / pronunciation. (你得注意你的工作/发音。)