对于停等流量控制，为了发送n个数据包，需要（）个确认帧。
A.n
B.2n
C.n-1
D.n+1
参考答案：D
吮小指或食指指习惯造成的错畸形表现有（）
A.单侧后牙反
B.前牙反
C.牙弓狭窄、上前牙前突
D.局部小开
E.下前牙拥挤
The teacher ______ my mobile phone because I used it in class.
[ ]
A. took out
B. took away
C. took off
D. took place
