弯管的局部损失主要包括()两部分。A.管壁摩擦损失和涡流损失; B.涡流损失和二次流

题型:单项选择题

问题:

弯管的局部损失主要包括()两部分。

A.管壁摩擦损失和涡流损失;

B.涡流损失和二次流损失;

C.管壁摩擦损失和二次损失;

D.管壁摩擦损失和撞击损失。

考点:汽轮机检修汽轮机运行与检修汽轮机运行与检修题库
题型:单项选择题

下列构成煤的可燃部分是()。

A.水分

B.灰分

C.挥发分

D.固定碳

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现有碳酸盐矿石(主要成分是BaCO3和CaCO3),要从该矿石中分离出BaCO3,并尽可能除去Ca2+

分离要求:A、原料只有矿石、水和燃料,不另用其他化学原料;

B:Ca2+含量越低越好.

(1)下图是分离的实验步骤,在箭头上方或下方注明反应所需的条件、方法或所需物质,在方框内写出每步所得产物的化学式.

(2)写出反应的化学方程式:

由A→B:______

由B→C:______

由D→E:______.

题型:单项选择题

阅读理解

     In a survey of 1,500 European hotel managers, Americans were ranked second, behind the Japanese,

as the world's best tourists. In the survey, conducted in April by the online travel site Expedia's German

branch, Americans were seen as the most likely to try to speak a foreign language and the most interested

in tasting local food.

     Americans came in third, behind the Japanese and British, as the "most polite" tourists, and third, behind the Japanese and Germans, as "best behaved". And ---- Americans were ranked far and away as the

world's most generous tippers and biggest spenders.

     On the other hand, Americans were seen as the shabbiest(破旧的) dressers, the most likely to

complain and the second noisiest. Who is louder? Only the Italians.

     Some of the other findings: Russians were as the least polite travelers, followed by the Israelis and

French. The stingiest(吝啬的) tippers: the Germans, followed by the French and Israelis.

Italians, by far, were ranked as the best dressers, followed by the French and Spanish. In terms of bad

dressing, the British were a distant second to Americans, followed by the Germans.

     Who's the most unwilling to try speaking in a foreign language? The French, the British and the Italians,

in that order.

     The Chinese are the most reluctant to taste foreign food, followed closely by ---- this is strange ---- the British, whose home cuisine is probably the world's most seriously laughed at ( a little unfairly, perhaps).

     And, finally, the overall award for "worst tourist in the world" goes to the French, with the Indians and

Chinese.

1. The writer presents the passage here hoping to _____.

A. praise some travelers              

B. criticize some travelers

C. present the result of a survey        

D. encourage people to travel

2. Considering the best behavior, the tourists ranking second are from ____.

A. Britain      

B. America    

C. Japan    

D. Germany

3. According to the survey, the worst dressers in tourists are ___.

A. the British  

B. the Americans    

C. the Germans  

D. the Spanish

4. The underlined word "cuisine" can be replaced by ___.

A. cooking    

B. decoration      

C. education    

D. management

题型:单项选择题

石油及石油产品按火灾危险性大小的分级标准是依据各油品的()。

A.自燃点

B.燃点

C.十六烷值

D.闪点

题型:单项选择题

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