1、competition 指竞争、角逐等行为时，是个抽象名词，不可数。competition 作“比赛；竞赛”解时，是可数名词，有数的变化。
2、the very notion of price competition is foreign to many schools。价格竞争这个概念对于许多学校都很陌生。
3、there's been some fierce competition for the title。夺冠之争一直都相当激烈。
4、i have to change my approach, the competition is too good now。我得改变方法，现在的竞争对手太强。