挥手道别时应该注意（）
A、集体站直
B、目视对方
C、手臂前伸
D、掌心朝外
E、左右挥动
参考答案：A, B, C, D, E
The article is ________ more difficult than that one, so I think I can understand it with the help of a dictionary.
A．much
B．quite
C．very
D．a little
流体流动的雷诺数越大，流体流动的阻力系数也越大。
