举重是我国的优势体育项目。一位身高180cm的运动员和一位身高160cm的运动员，在挺举项目中用相同时间，把同样重的杠钤举起，如图所示。如果他们对杠钤所做的功分别为W₁和W₂，功率分别为P₁和P₂，则下列关系式中正确的是（   ）

   All students need to have good study habits(习惯). When you have good study habits, you can learn things quickly. You also remember them easily. Do you like to study in the living-room? This is not a good place because it is usuallytoo noisy. You need to study in a quiet place, like your bedroom. A quiet place will help you only think about one thing, and you will learn better. Before you begin to study, do not forget to clean your desk. A good desk light is important, too. You are feeling tired easily if there is not enough(足够的) light.