be careful的用法和樣例：
例句
- Be careful about what you say.
對你所說的話要小心。 - You should be careful when making a promise.
你應當謹慎做出承諾。 - Be careful!
一定要小心！ - Be careful crossing the road.
過馬路要當心。 - Be careful of that viper; he is dangerous.
小心那個陰險的人，他很危險。 - Be careful of that chair; it's a bit rocky.
當心，那椅子有些不穩。 - Be careful when you cross the road.
過馬路時要當心。 - Be careful not to lose too much liquid by evaporation.
小心，不要因為蒸發作用而失掉過多的水份。
