be careful后加什么介词

be careful后跟about、of、with等介词；

be careful可单独使用，也可跟动词不定式或of／with短语；

be careful

小心;当心;注意

You\'ll have to be careful how you frame the question.

如何提出这个问题，你得慎重。

Be careful you don\'t trip up on the step.

你小心别在台阶上绊倒了。

Be careful you don\'t knock your head on this low beam.

小心，别把头撞在这矮梁上。

Be careful not to cross the line.

小心别越过道路的中界线。