题目

化学变化的本质是（    ） A．发热发光         B．生成新物质      C．颜色发生变化     D．状态发生变化 答案：BShe will tell us why she feels so strongly that each of us has a role ________ in making the earth a better place to live in. A. to have played 　　　　　　　　　　　　　 B. to play C. to be played 　　　　　　　　　　　　　　 D. to be playing