给水泵严重汽化的现象，入口管和泵内发生不正常的（）；给水泵出口压力（）。
参考答案：噪音；摆动和降低
The population of many Alaskan cities has ______ doubled in the past three years.
A．as great as
B．as many as
C． more than
D．larger than
UM71轨道电路用0.15Ω标准分路电阻线分路，死区段长度不应大于（）m。
