天然气加气站按（）分为快充站、慢充站和混合充气站。
A、规模；
B、气站气源；
C、气站设备总体设置；
D、车辆充气时间.
参考答案：D
用所给单词的适当形式填空。
1. He was a natural leader, and when he ____ (command), everyone obeyed.
2. Theory ____ (base) on practice and in turn serves practice.
3. I am just ____ (request) that you keep him safe.
4. The girl ____ (recognize) her father and cried at once.
5. The meeting ____ (expect) to end in the morning.
手术后易发生“石头心”的疾病是()
A．二尖瓣狭窄
B．二尖瓣关闭不全
C．主动脉瓣狭窄
D．主动脉瓣关闭不全
E．主动脉瓣狭窄并关闭不全
