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问题 选择题

跨过定滑轮的绳的一端挂一吊板，另一端被吊板上的人拉住，如图所示，已知人的质量为70kg，吊板的质量为10kg，绳及定滑轮的质量、滑轮的摩擦均可不计，取重力加速度g=10m/s2．当人以440N的力拉绳时，人与吊板的加速度a和人对吊板的压力F分别为（　　）

A．a=1.0 m/s2．F=330N

B．a=1.0 m/s2．F=260N

C．a=3.0 m/s2．F=110N

D．a=3.0 m/s2．F=50N

答案

以人与吊板整体为研究对象，根据牛顿第二定律得：

加速度a=

2T-(M+m)g
M+m
=
2×440-80×10
80
m/s2=1m/s2

再对吊板研究，则有：T-（mg+F）=ma，得到：F=T-ma-mg=440N-10×11N=330N

故选A

单项选择题

Are you a man or a mouse When people ask this question they want to know (1) you think you are a (2) person or a coward. But you will never really know the answer to this question (3) you are tested in real life. Some people (4) they are brave but when they come face to face with real (5) , they act like cowards. Others think of themselves as cowards, but when they meet danger, they act like (6) .Lenny had always thought of himself as a (7) person. He got worried before examinations. He worried about his job and health. All he wanted in life was to be safe and healthy. (8) , on January 15th, 2002, a plane crashed into the Potomac River in Washington. Lenny went to the river to See what was happening. He saw a woman in the (9) water. Lenny did not feel afraid. He kept very (10) and did a very dangerous thing. He jumped into the Potomac, (11) to the woman, and kept her head (12) the water. Seventy-eight people died that day. Thanks to Lenny, it was not (13) .When you are in a very (14) situation and feel afraid, the body automatically produces a chemical in the blood. The chemical is called adrenalin. (15) adrenalin in the blood system, you actually feel per and per and are (16) to fight or run away. However, when you are absolutely terrified, the body can produce too much adrenalin. Where this (17) , the muscles become very hard and you find you (18) move at all. You are then paralyzed with fear. This is (19) when we are very frightened, we sometimes say we’re "petrified". This word comes from the Greek word "petros", which means "stone". We are (20) frightened that we become stonelike.

第（18）空应选择（）

A．needn’t

B．can’t

C．mustn’t

D．shouldn’t
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单项选择题

关于“直客式”汽车贷款的流程，下列表述正确的一项是( )。

A．选车→准备所需资料→与经销商签订购买合同→银行在经销商或第三方的协助下做资信情况调查→银行审批、放款→客户提车
B．准备所需材料→选车→与经销商签订购买合同→银行在经销商或第三方的协助下做资信情况调查→银行审批、放款→客户提车
C．到银行网点填写个人汽车贷款借款申请书→银行对客户进行资信调查→银行审批贷款→客户与银行签订借款合同→客户到经销商处选定车辆并向银行缴纳购车首付→银行代理提车、上户和办理抵押登记手续→银行放款→客户提车
D．到银行网点填写个人汽车贷款借款申请书→银行对客户进行资信调查→银行审批贷款→客户与银行签订借款合同→客户到经销商处选定车辆并向银行缴纳购车首付→个人提车、上户和办理抵押登记手续
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