You should be careful of Ian - he can be pretty ruthless if anyone gets in his way.你得当心伊恩。谁要是妨碍了他，他就会变得冷酷无情的。I'm not arguing in favor of cannabis. I'm just saying we should be careful of overreaction.我并非是在为赞成吸食大麻而争辩，我只是想说我们应该小心不要反应过激。They had to be careful of floating chunks of ice.他们必须当心大块浮冰。