建筑基坑采用集水明排时,排水沟和集水井可按下列规定布置,其中()是不正确的。A.排水

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问题:

建筑基坑采用集水明排时,排水沟和集水井可按下列规定布置,其中()是不正确的。

A.排水沟和集水井宜布置在拟建建筑基础边净距0.4m以外

B.排水沟底面应比挖土底面低0.2m

C.集水井底面应比排水沟底面低0.5m以上

D.排水沟边缘离开坡角不应小于0.3m

考点:注册土木工程师岩土工程专业知识专业知识
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若等比数列{an}的前n项和Sn=2·3n+a (a为常数),则a=_____.

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某同学为研究滑动摩擦力与哪些因素有关设计了图10所示实验。

他用弹簧秤水平拉动木块在水平面上作匀速直线运动,读出并记录弹簧秤的读数。实验中改变被拉木块的数量、改变接触面的材料、改变接触面积的大小及改变木块速度的大小,并将若干次实验数据记录在下表中.试根据该同学的实验数据,分析总结并回答下列问题

实验次数接触面材料拉动木块数木块放置情况木块运动速度弹簧秤读数(N)
1木板1平放v较小3.50
2木板1平放v较大3.50
3木板1侧放v较小3.50
4木板2平放v较小7.00
5化纤地毯1平放v较小8.00
6化纤地毯1侧放v较大8.00
7化纤地毯2平放v较小16.00
(1)物体间的滑动摩擦力的大小与哪些因素有关?有什么关系?

(2)物体间的滑动摩擦力的大小与哪些因素是无关的?

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下列各种提高热机效率的方法中,不可行的是(  )

A.减少各种热损失

B.采取少消耗总能量的办法

C.添加润滑油减少机械部件的摩擦

D.充分利用废弃的量,如建热电站,利用发电产生的高温废弃向居民和工厂供热

题型:单项选择题

Passage Two

If there is one thing I’m sure about, it is that in a hundred years from now we will still be reading newspapers. It is not that newspapers are a necessity. Even now some people get most of their news from television or radio. Many buy a paper only on Saturday or Sunday. But for most people reading a newspaper has become a habit passed down from generation to generation.

The nature of what is news may change. What basically makes news is what affects our lives—the big political stories, the coverage of the wars, earthquakes and other disasters, will continue much the same. I think there will be more coverage of scientific research, though. It’s already happening in areas that may directly affect our lives, like genetic engineering. In the future, I think there will be more coverage of scientific explanations of why we feel as we do—as we develop a better understanding of how the brain operates and what our feelings really are.

It’s quite possible that in the next century newspapers will be transmitted electronically from Fleet Street and printed out in our own home. In fact, I’m pretty sure that how it will happen in the future. You will probably be able to choose from a menu, making up your own newspaper by picking out the things you want to read--sports and international news, etc.

I think people have got it wrong when they talk about competition between the different media. They actually feed off each other. Some people once foresaw that television would kill off newspapers, but that hasn’t happened. What is read on the printed page lasts longer than pictures on a screen or sound lost in the air. And as for the Internet, it’s never really pleasant to read something just on a screen.

What is the best title for the passage()

A.The Best Way to Get News

B.The Changes of Media

C.Make Your Own Newspaper

D.The Future of Newspaper

题型:单项选择题

增强CT扫描,哪种病变不增强()

A.垂体腺瘤 

B.动脉瘤 

C.脑膜瘤 

D.蛛网膜囊肿 

E.髓质细胞瘤

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