Be very careful with this stuff, it can be dangerous if it isn't handled properly.

对这东西要小心，处理得不好可能会发生危险。

《柯林斯英汉双解大词典》

One should be very careful with what he thinks.

每个人都应该对他的想法谨慎。

youdao

You must be very careful with this sharp knife.

你用这把锋利的刀子时必须很小心。

youdao

Be careful C it is very sharp, with teeth just like a saw.

VOA: special.2009.06.30

And if you've typed in l when you should've 1 typed a 1, or a 1 when you should've typed an l, you're likely to miss it. If you've made a mistake with upper and lower case. Things like that. So just be very careful looking at that.

如果你本来想打，1，的时候,却输成了，l，或者打，l，的时候输成了，你很可能注意不到这个错误,如果你把大小写弄混了也是一样,要注意这个错误。

麻省理工公开课 - 计算机科学及编程导论课程节选

But if you do have private insurance, you should be very careful with this data.

NPR: 3 min 45 sec

You may be very careful with your credit card, but the merchants charging it may not.

FORBES: You better watch out: Online shopping attacks are coming to town.

"Any athlete needs to be very careful with what they take, " he told BBC News Online.

BBC: Myostatin controls the growth of muscles