Have a nice time, dear, and drive carefully.

好好玩，亲爱的，要小心驾驶。

a vast series of deliberate and carefully planned thefts.

多起精心策划、周密安排的盗窃案件。

He should think carefully about actions like this which play into the hands of his opponents.

他应该留神这类对对手有利的行为。