问题 选择题

动物为了适应自身生存的环境,进化出了符合一定物理规律的身体部位.对此,从物理学的角度给出的解释错误的是(  )

A.泥鳅体表有一层滑黏的液体,可减小摩擦以利于钻入泥洞

B.鱼主要靠鳔的调节作用从而改变自身重力来实现上浮和下沉

C.啄木鸟的喙很尖细,可以增大压强,从而凿开树干,捉到里面的虫子

D.壁虎的脚掌上有许多“吸盘”,从而利用大气压使其在天花板上不会掉下来

答案

A、泥鳅的体表渗出的黏液,是在压力一定时,减小接触面的粗糙程度来减小摩擦力,利于钻入泥洞.不符合题意.

B、∵Fvg,水面下游动的鱼通过鳔的调节时期体积变大(排开水的体积变大),

∴鱼受到水的浮力变大,而鱼的重力不变,

即鱼主要靠鳔的调节作用从而改变浮力的大小来实现上浮和下沉.说法错误,符合题意.

C、啄木鸟的嘴很尖细,就是在压力一定时通过减小受力面积的方法来增大压强的,便于凿开树干,吃到里面的虫子.不符合题意.

D、壁虎的脚掌上有许多“吸盘”,是把盘内的空气挤出,外界大气压把吸盘压在天花板上,从使其在天花板上也不会掉下来.不符合题意.

故选B.

阅读理解

阅读理解,回答问题。

     As teenagers, you have many dreams. These dreams can be very big, such as winning the Nobel

Prize, or they can be small. You may just want to become one of the ten best students in your class.

Once you find a dream, what do you do with it? Do you ever try to make your dream true?

     Follow Your Heart by Australian writer Andrews tells us that making our dreams true is life's

biggest challenge (挑战).

     In fact, everyone can make his dream come true. The first thing you must do is to remember

what your dream is.

     Don't let it leave your heart. Keep telling yourself what you want. Do this step by step and your

dream will come true faster because a big dream is, in fact, many small dreams.

    You must also never give up your dream.

     There will be difficulties on the road to your dreams. But the biggest difficulty comes from yourself.

You may think you're not very good at some school subjects, or it is impossible for you to become a

writer. These kinds of thoughts stop you from getting your dream, the book says.

     You need to decide what is the most important. Studying instead of watching TV will lead to better

exam results, while saving five yuan instead of buying an ice cream means you can buy a new book. As

you get closer to your dream, it may change a little. This is good as you have the chance to learn more

skills and find new interests.

1. Translate the sentence underlined in paragraph 7 into Chinese.

    ________________________________________________________________________

2. Find out the sentences from the passage that stand for "the biggest difficulty comes from yourself".

    ________________________________________________________________________

3. What should you do if you want to make your dream come true? (至少两条)

    ________________________________________________________________________

4. What's the main idea of the last paragraph?

    ________________________________________________________________________

5. 请给短文拟定一个适当的英文标题。

   ________________________________________________________________________

多项选择题