play a/the role 发挥作用；扮演角色（have effect on; act the part of）

　　例句：

　　1. The faculties and administrations know the important role intemational students play on the typical college campus.

　　教职人员和管理部门都知道外国学生在典型的大学校园中发挥的重要作用。

　　2．Who plays the role of Hamlet?

　　谁扮演哈姆雷特？

　　play it by ear 随机应变

　　A: Marty, are you doing anything special for your presentation in political science tomorrow?

　　A：马蒂，你现在是不是在专门准备明天的政治学课的发言？

　　B: Not really. Because the class so often turns into a discussion, l've decided to play it by ear.

　　B：也不是。因为这门课经常会变成讨论，我就决定随机应变了。

　　play the clarinet 吹单簧管（演奏乐器是学生课余经常做的事情，故也应注意掌握）

　　例句：

　　He played the clarinet in the club every weekend.

　　每个周来他都在一家俱乐部吹单簧管。

　　play the trumpet 吹喇叭

　　例句：

　　Just imagine Mr.Show playing the trumpet．

　　想一想肖先生竟会吹喇叭。

　　play the violin 拉小提琴

　　例句：She began playing the violin when she was nine．

　　她九岁的时候就开始拉小提琴。