Be careful of the nettles—they sting!

小心给荨麻扎着—荨麻有刺！

They had to be careful of floating chunks of ice.

他们不得不小心漂浮着的厚冰块。

Be careful of your actions.

留意你的行为。

He's a bad egg. Be careful of him.

他是个坏蛋。要小心他。

Be careful of the flu.

小心染上流行性感冒。