题目

 8. “Please make ________  at home,” the landlady said to the children.    A. yourself            B. you               C. yourselves         D. Themselves 答案：C6．摩托车的消声器是在声源处减弱噪声的；放鞭炮时，小孩都会用手捂住耳朵，这是在人耳处减弱噪声．