下列说法中错误的是() A.两个相似的流动必须能被同一微分方程组所描述 B.当雷诺准

题型:单项选择题

问题:

下列说法中错误的是()

A.两个相似的流动必须能被同一微分方程组所描述

B.当雷诺准则和傅劳德准则同时满足时,马赫数准则将自动满足

C.实际流动中旋涡都没有保持性,因为粘性是促使旋涡产生、发展、消失的最重要因素

D.N-S方程的物理含义是单位质量流体的质量力、压力梯度和粘性力之间的平衡

考点:航空、航天科学技术空气动力学空气动力学题库
题型:单项选择题

阅读理解.

        A taxi hit a truck. A policeman spoke to the taxi driver and the truck driver. He also spoke to Tom.  He was a witness (目击者).  This is what they said.

TRUCK DRIVER: I was driving from the air- port to Newton. A car crossed the road, so I slowed

                             down.  I did not stop. A taxi hit the back of my truck. Nobody was seriously hurt but

                             both cars were damaged(受损害).

TAXI DRIVER: I was driving behind a truck a few kilometers to Newton. The truck stopped suddenly.

                         The driver did not give me a warning (警告). I was driving very slowly. I could not pass

                         the truck because there were two cars coming near to Newton. My taxi hit the truck, and

                           some glass cut my left hand.

TOM: I was watching the traffic about a kilometer from the airport. A truck was going to Newton. It

          was not going very quickly. There was a taxi about two hundred meters behind the truck. It was

          going fast. When the truck slowed down, the taxi hit it. The taxi driver was not looking at the truck.            He was looking out of the window at some-thing else. My friend saw the accident, too. Tom's

          friend spoke to the policeman and agreed with Tom.

1.  How many people are mentioned (提到)  in the story ? 

A. Three.          

B. Four.

C. Five.            

D. Six.

2. The truck was hit on the way __________. 

A. to the airport      

B. to the police station

C. to Newton        

D. home

3. From the story, we know __________didn't tell the truth. 

A. the truck driver      

B. Tom

C. the taxi driver      

D. Tom's friend

4. In fact, Tom's friend was also a __________. 

A. witness            

B. driver

C. policeman          

D. cleaner

5. What's the best title(标题) for this passage?  

A. A Taxi Driver.      

B. A Traffic Accident.

C. A Story of Tom.      

D. A Truck Driver.

题型:单项选择题

西安事变与重庆谈判都是中国近代史上的重大历史事件,两者的相同点有

①张 * * 都直接参与其中②中 * * 党都作出了积极的努力

③都初步出现了有利于中 * * 的局面④都预示着团结抗日新局面的到来[ ]

A.①②

B.③④

C.①④

D.②③

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冷库围护结构隔热性能主要指标是隔热层的()。

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《野生药材资源保护管理条例》中收载了物种数是()

A.13种

B.24种

C.35种

D.76种

E.42种

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关于绿色信贷,银行业金融机构应该如何开展()

A.加强绿色信贷理念宣传教育

B.推行绿色办公

C.提高集约化管理水平

D.重视自身的环境和社会表现

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