问题 问答题

A、B量物体均处于静止状态,做出A物体受力图,并标注力的符号,标出其大小,如图,其中mA=10千克,mB=10千克.

答案

B受两个力,拉力和重力,所以T=mBg=100N.对A受重力、支持力、拉力和摩擦力.重力G=100N,支持力N=100N,T=100N,摩擦力f=100N.受力如图.

故答案为:如图所示.

阅读理解

Why do I volunteer with Big brothers / Big sisters of America? I have many reasons. Perhaps the biggest reason is that people once volunteered to help me.

Years ago, I was on the other side of the table. I was lonely and I felt lost. It’s a little embarrassing to talk about it now, but whatever the right direction in life was, I was going the opposite way. More than once, I found myself on the wrong path. If someone hadn’t stepped in when he did, I probably wouldn’t even be here now. I’d rather be in a prison or somewhere a lot smaller and deeper.

I’ve seen the work that big brothers / sisters have been doing all over the country and I’m pleased to be part of it. I’ve never done anything that made me prouder than my volunteer work. Big brothers and sisters helped me get over sadness and depression as soon as possible. Then, if I can help anyone like they helped me, I am willing to serve for as long as they will have me serve them. There are no words to describe the joy I get from helping somebody turn their life around. Every time I think that that’s me now, I’m proud and happy.

Volunteering is how I want to leave my mark on the world. I recommend volunteering work to everybody, especially to somebody who isn’t sure where they are going in life. Helping someone find their path is often the best way to find yours. Be a volunteer, and you will find your purpose in life.

小题1:What’s the main reason why the writer volunteers?

A.He has a lot of free time.

B.He is lonely and wants to be with others.

C.He wants others to know he is a good man.

D.He is grateful for what volunteers once did for him.小题2:It is implied in Paragraph3 that the writer __________.

A.is eager to help others

B.often feels sad and depressed

C.hopes he will be helped at any time

D.travels around the country to help others小题3:We can infer from the passage that the writer probably __________.

A.spent some days in prison

B.didn’t know his purpose in life

C.is dissatisfied with his life

D.doesn’t live a meaningful life小题4:What is the writer’s purpose in writing this passage?

A.To share his past with us.

B.to ask for some volunteer work.

C.To encourage us to enjoy our life.

D.To call on us to do volunteer work.

单项选择题