caution 
英 [ˈkɔːʃən]  美 [ˈkɔʃən] 
n. 小心，谨慎；警告，告诫；担保

v. 警告，告诫

例句：
You must proceed with extreme caution. 

你必须特别小心行事。

Extreme caution should be exercised when buying part-worn tyres. 

购买局部磨损的轮胎时要特别小心。

My tutor solemnly cautioned me that I might not pass my exams. 

指导老师严肃地告诫我说，我有可能考试不及格。

He cautioned that opposition attacks on the ruling party would not further political co-operation. 

他告诫说，反对党对执政党的攻击不会促进政治合作。