面对考试失利，有些同学垂头丧气，有些同学则暗下决心迎头赶上。同学们的不同反应主要说明（  ） 

下列属于化学变化的是（　　）

阅读短文，根据短文内容选择正确的答案。

    Coffee has become the most popular American drink. Today people in the United States drink more coffee than（比）people in any of the other countries. People drink coffee at breakfast, at lunch, at dinner, and between meals. They drink hot coffee or coffee with ice in it. They drink it at work and at home. They eat coffee ice-cream and coffee candy（糖果）. Coffee is black and very strong. Different people like to drink it in different ways. Some people like coffee with cream or sugar in it. Other people like coffee with both cream and sugar in it. In all ways it is served（提供服务）. Coffee has become an international（国际的）drink.