水泵卡圈可防止泵内高压侧水流回低压侧，水泵效率降低。
参考答案：对
_______ ,and the information you need will come out of your computer screen.
A．Just a moment
B．If you just wait a moment
C．Just waiting a moment
D．Just to wait a moment
腹穿液为血性，臭味较重，应为
A．结核性腹膜炎B．胃、十二指肠溃疡急性穿孔C．急性阑尾炎D．绞窄性肠梗阻E．实质脏器损伤
