Be careful --her .A with B to C about

本题选择A with.
1) be careful to do something=you make sure that you do it.你确定你能做某事.
2) be careful about doing something=you think that what they intend to do is probably wrong,and that they should think seriously before they do it.告诉别人在做某事之前一定三思而行.
3) be careful with后面可以跟人或者事物,表明当心,谨慎