题目

    Do you know how to play a game called “Musical Chairs”？ It is easy to play and most people enjoy it. All you need are some chairs， some people and some way of making music. You may use a piano or any other musical instrument， if someone can play it. You may use a tape recorder. You can even use a radio.     Put the chairs in a row. The chairs may be put in twos， back to back. A better way is to have the chairs in one row with each chair facing in the opposite direction to the chair next to it.     The game is easy. When the music starts， the players walk ro当a=1，b=-3时，代数式的值是A.2B.0C.3D.