一列波在介质中向某一方向传播，如图所示为此波在某一时刻的波形图，并且此时振动还只发生在M、N之间，已知此波的周期为T，Q质点速度方向在波形图中是向下的，下面说法中正确的是（　　）

A．波源是M，由波源起振开始计时，P点已经振动时间T

B．波源是N，由波源起振开始计时，P点已经振动时间

C．波源是N，由波源起振开始计时，P点已经振动时间

D．波源是M，由波源起振开始计时，P点已经振动时间

短文填空 根据短文内容及首字母提示，补全空格内单词，使短文完整、通顺。（请在答题纸上写出完整单词）（每空一词；共10空，每空1分，满分10分）

We are beautiful red-crowned cranes. We have red caps on top of our heads. You may t 小题1: the caps are our feathers. In fact, they are combs(冠). We are one of the l  小题2:birds in size in the world. We are the heaviest cranes. An adult red-crowned crane can w 小题3:  11 kilograms when it grows up. We are good at d 小题4:  . I think we are the most beautiful dancers of all the birds. We are also good s  小题5: . We sing loudly and beautifully. We are good at flying as well. We fly to warm East Asia when s 小题6:   comes. We give birth to baby cranes there. We like to live together on wetlands in Southwest China and some other places. We l 小题7:   mainly on worms and small fish. We like to live in long grasses. Water and grasses are i 小题8:for us. But sometimes, life is harder these years. We are one of the most endangered birds in the world now. People keep taking our living areas t  小题9:  make farms and build houses. We don’t have enough space to live. And we don’t have enough food to feed our babies because people fish and hunt too m 小题10: . Can you help us!