从事营业性道路运输的驾驶员必须持证上岗，否则属于（）行为。
参考答案：违规
如图，水下一半球形侧盖，半径R=1.5m，水深h=2.0m，作用在半球的静水总压力大小是( )kN。
A．277.1
B．207.8
C．138.5
D．98.8
Wherever such an area is located, it will be immediately ______ by the enemy if armed forces are lacking.
A．taken
B．caught
C．occupied
D．kept
