为了解健康促进规划的进展情况，发现存在的问题并及时改进而进行的评价是（） A.形成评

一列简谐横波在x轴上传播（沿y轴方向振动）．已知x=12cm处质点的振动图线如图甲，x=18cm处质点的振动图线如图乙．根据这两质点的振动图线，判断下列表述正确的是（　　）

A．若波沿x轴正向传播，波速最大值为

B．若波沿x轴负向传播，波速最大值为

C．若波沿x轴正向传播，波速可能为2 cm/s

D．若波沿x轴负向传播，波速可能为2 cm/s

In an appropriate communication model between a sender and a receiver．all the following statements are correct EXCEPT：

A．Noise should be minimize

B．Receiver must decode and reply back to the messag

C．Receiver should acknowledge and agree with the message sent by the sende

D．Sender must choose right way to send the message

运输大巷常布置在煤层底板岩石（）

A、上

B、中

C、下

D、底部

As we are ______ the market for Table Cloth, we should be glad if you would send us your best quotation.

A．in
B．on
C．entering
D．at