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【多选题】
两敞口容器间用离心泵运输液体,改变下列参数,能使泵的工作点发生改变的是( )。A.
泵的转速
B.
泵出口阀门的开度
C.
被输送液体的密度
D.
叶轮的直径
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举一反三
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A.
Which
B.
How soon
C.
What time
D.
How long
【单选题】_ ____ do you water the flowers? _ Three times a week. [ ]
A.
How long
B.
How soon
C.
How much
D.
How often
【单选题】— ______ do you help the old man with the housework? — Once a week. [ ]
A.
How soon
B.
How long
C.
How often
D.
How many
【单选题】—_____ has Miss. Jones been in Beijing? —For two and a half years. [ ]
A.
How far
B.
How long
C.
How often
D.
How soon
【单选题】—_____ has your father lived in the town? —Six years. [ ]
A.
How many
B.
How soon
C.
How long
D.
How often
【单选题】--- How is the _______ in Xiangyang ? --- It’s getting worse and worse. There are always long lines of cars on roads .
A.
culture
B.
food
C.
weather
D.
traffic
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