切牙切端唇向移动1mm后双侧可得间隙 （）
A.1mm
B.2.5mm
C.2mm
D.3.5mm
E.4mm
参考答案：C
You _______ eat in class. [ ]
A. don't
B. can't
C. not
D. no
管槽内对流传热的入口效应是指（）
