柴油机活塞上安装有气环和油环，两者的安装位置是（）。
A.气环在油环之上
B.油环在汽环之上
C.汽环、油环、汽环
D.油环、汽环、油环
参考答案：A
--- Why do you choose to go to Meiling Middle School?
---Everyone says the teachers there are strict not only ____ their students but also ____ their work.
A．with, on
B．in , with
C．in, on
D．with, in
有关氯胺酮的特征，下列哪各说法不正确（）
A.止痛性能极强
B.麻醉作用快速、短效
C.具有类似致痛作用
D.能降低脑氧耗量，对脑缺氧有保护意义
E.可使心率增速、血压升高及心排出量上升
