摩托车的排气管安装消音器,属于哪种减弱噪音的方式( )
A.在人耳处减弱
B.在声源处减弱
C.在传播过程中减弱
D.以上三个方法都用到了
摩托车安装消音器是在声源处减弱噪声;
故选B.
---Do you mind my smoking here?
--- __________. Look at the sign! It says, "No smoking!"
A.Never mind.
B.Of course.
C.You’d better not.
D.No, I don’t.
There is no possibility ________ he will keep his word.He is always telling lies.
A.how
B.whether
C.when
D.that