【单选题】【消耗次数：1】
离心泵扬程的意义 。
①
A、泵的实际升扬高度
②
B、泵的吸液高度
③
C、液体出泵和进泵的压差换算成的液注高度
④
D、单位重量液体出泵和进泵的机械能差值
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相关题目
【单选题】
倘若开大离心泵出口阀门，提高泵的输液量，会引起 。
①
A、泵的效率提高
②
B、泵的效率降低
③
C、泵的效率可能提高也可能降低
④
D、泵的效率只决定于泵的结构及泵的转速，与流量变化无关
【单选题】
在某单泵输液的管路中，并联一台同一型号的离心泵，单泵与并联双泵的输液效果为————。
①
并联的输液量将是单泵的两倍
②
并联的扬程将是单泵的两倍
③
并联的能耗将是单泵的两倍
④
并联的输液量、扬程或能耗都不会是单泵的两倍
【单选题】
离心泵铭牌上标明的扬程m可理解为 。
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A、该泵在规定转速下可以将20℃的水升扬的高度
②
B、该泵在规定转速、最高效率下将20℃的水升扬的高度
③
C、该泵在规定转速下对20℃的水提供的压头
④
D、该泵在规定转速、最高效率下对20℃的水提供的压头
随机题目
【单选题】
Goats are being hired to do the work of people near San Diego. The fires that occurred in Hillborbough four years ago destroyed thirty homes, most of which have been rebuilt. While people were rebuilding the homes, the grasses and bushes were growing back. The area is now so overgrown in bushes that there is again a major danger of fire.The city government put up bids to remove the bushes. The lowest bid they received was $50,000—and that was if the city provided breakfast and lunch for the workers for the six weeks it would take to clear the overgrown area. The city only wanted to give unlimited coffee and a piece of bread a day for each person. When that offer was rejected, the city asked for help on its website.A sheepherder in Montanta and a goat-keeper in San Bernardino read about the city’s plight（困境）while surfing the Web. They both offered to do the job for $25,000. The city government chose the goat-keeper because he lived closer. When he was told that the city dump（垃圾场）was overflowing , the goat-keeper said, “No problem. My goats will eat everything in your dump, except the car engines, of course.” So, for another $5,000, the city killed two birds with one stone. If all goes well, they will invite the goat-keeper and his “family” back every three years. The goat-keeper said that he would probably visit San Diego while his goats were in the dump.What are the “two birds” that the city government kills with only one stone?
①
Both the sheepherder and goat-keeper will work for the city for $25,000.
②
The danger of fire and providing breakfast and lunch for the work crews.
③
The danger of fire and the overflowing dump.
④
The city government can save some money and the goat-keeper has a new job.
【单选题】
You have to work hard if you want to __________ in your courses.
①
achieve
②
succeed
③
win
④
beat
【单选题】
Susan: How do you do, Mrs. White.Mrs. White: How do you do, Susan. I’m glad you can join us. __________
①
Dont be shy.
②
Please feel natural.
③
Make yourself at home.
④
Feel all right here.
【单选题】
I ___________ a short rest before we continue the work.
①
produce
②
publish
③
propose
④
pull
【单选题】
Visitor: How do I get to the bank? I have no knowledge of this area. Policeman: Cross the road and turn left at the other side. __________ for about 100 meters and the bank is to your left.
①
Continue your walking
②
Keep going straight
③
Go along
④
Go on walking
【判断题】
答题说明：句子没有语法错误请选择“正确”，有语法错误请选择“错误”Jim wasnt a coward and he hated the Fascists deeply.
①
正确
②
错误
【判断题】
答题说明：句子没有语法错误请选择“正确”，有语法错误请选择“错误”Before Ford introduced the assembly line, each car was build by hand.
①
正确
②
错误
【判断题】
We are all worried about him with that, but he thinks nothing of it.划线部分应该翻译成“无法理解”
①
正确
②
错误