问题 选择题

形状不同的物体都浸没在同种液体中,所受浮力相等,它们(  )

A.体积一定相等

B.质量一定相等

C.密度一定相等

D.一定都是实心物体

答案

由阿基米德原理公式F=GgV可知,不同物体浸在同种液体中时,所受浮力大小与物体排开液体的体积成正比.因为形状不同的物体所受浮力相等,所以它们排开液体的体积是相等的,又因为它们都浸没在液体中,V=V,所以它们的体积也一定相等.

故选 A.

单项选择题 共用题干题
阅读理解

阅读理解。

     In my thirty years as a Time Management speaker, I have observed a lot of what we can and should

not do to increase our daily result. Time Management is not necessarily working harder, but quicker and

smarter. Sometimes our mistakes will keep us from running at a full pace. Here are the top four Time

Management mistakes we should all avoid to help us to increase our daily success.

     a). Start your day without a plan of action. If so, you will have worked hard but may not have done

enough of right things. Time Management is not doing the wrong things quicker. Time Management is

doing the right things.

     b). Work with a messy(杂乱的) desk or work areas. Studies have shown that the person who works with a messy desk spends one and a half hours per day looking for things. If you have ever visited the

office of a top manager, who is working with a clean desk environment, you will find that the manager

works effectively(有效地).

     c). Don't get enough sleep. Studies show that nearly 75% of us complain on a regular basis, all

throughout our days, that we are tired. For most people, they get the quantity of sleep, but they lack the

quality of sleep. Their days are filled with so much stress that they are out of control, working harder but

maybe not smarter, that it's difficult to get a full night's sleep.

     d). Don't take a lunch break. Many do not take a lunch break, working through that period in the

hopes that it will give them more time to produce results. Studies have shown it may work just the

opposite. After doing what we do for several hours, we start to feel tired. A lunch break, even short,

gives us a chance to get our energy back again.

1. The purpose of this passage is to __________.

A. show how to become a speaker

B. explain the importance of Time Management

C. persuade us to get rid of bad habits

D. tell us to avoid Time Management mistakes

2.  We may know from the passage that Time Management is about ____________ . 

A. how to deal with a lunch break

B. how to get the quality of sleep 

C. how to do right things quicker and smarter

D. how to avoid doing the wrong things

3. What can we learn from the passage?  

A. Working with a plan of action can save one and a half hours per day.

B. Studies have shown that most people work with a messy desk.

C. People can't get a full night's sleep mainly because of too much stress.

D. The longer a lunch break is, the more efficiently people will work.

4. The author holds the following opinions EXCEPT ____________.

A. Time waits for no man.

B. Good order leads to great success.

C. A year's plan starts with spring.

D. No rest, no work.