Have you ever wondered why birds sing? Maybe you thought that they were just happy.  After all,you probably sing or whistle when you are happy.

    Some scientists believe that birds do sing some of the time just because they are happy. However,they sing most of the time for a very different reason. Their singing is actually a warning to other birds to stay out of their territory.

Do you know what a 'territory' is? A territory is an area that an animal,usually the male,claims(声称)as its own. Only he and his family are welcome there. No other families of the same kind are welcome. Your garden and house are your territory where only your family and friends are welcome. If a stranger should enter your territory and threaten(威胁)you,you might shout. Probably this would be enough to frighten him away.

If so,you have actually scared the stranger away without having to fight him. A bird does the same thing. But he expects an outsider almost any time,especially at nesting(筑巢)season. So he is screaming all the time,whether he can see an outsider or not. This screaming is what we call a bird's song,and it is usually enough to keep an outsider away.

Birds sing loudest in the spring when they are trying to attract a mate and warn others not to enter the territory of theirs..

     You can see that birds have a language of their own. Most of it has to do with attracting mates and setting up territories.

1. Some scientists believe that most of the time bird's singing is actually _______.

      A. away of warning              B. an expression of happiness

      C. an expression of anger          D. away of greeting

2.What is a bird's "territory"?.

      A. A place where families of other kinds are not accepted.

      B. A place where a bird may shut at the top of its voice

      C. An area for which birds fight against each other.

      D. An area which a bird considers to be its own.

3. Why do birds keep on singing at nesting season?

      A. Because they want to invite more friends.

      B. Because they want to find outsiders around.

      C. Because their singing helps frighten outsiders away.

      D. Because their singing helps remove their fears.

4.How does the writer explain bird's singing?

A. By comparing birds with human beings.    B. By reporting experiment results.

C. By describing birds' daily life.        D. By telling a bird's story.

 

During the day, you spend a lot of time running, jumping, laughing, eating, and talking. You use up a lot of energy(能量) , and by the end of the day you're tired. Sleep gives your body a chance to rest.

But your brain (大脑)and body are not completely at rest during sleep. While you sleep, your mind may think of the things that happened during the day. It keeps the important things in mind as memories(记忆). It also thinks about things you were worrying about, and you may wake up with answers to some of your problems.

You also grow while you sleep. The thing called "human growth hormone (荷尔蒙)" in the body helps you grow during sleep. This growth hormone also helps the body to repair itself.

Sleep helps your body to conserve energy too. You use up a lot of energy during your daily activities. But when you sleep, your body temperature falls, and your "metabolism" (新陈代谢) slows down. You are still using some energy, but much less than when you are awake and active.

Have you ever stayed up past your bedtime? Did you have difficulty getting up the next morning? Maybe you had problems seeing clearly or you cannot think clearly. That was your body's way of saying, "I need sleep!" A lack ( 缺乏) of sleep can stop your body and mind from working correctly.

1.What does "human growth hormone" do while people sleep?

A.It helps people rest well.

B.It helps repair the body.

C.It helps answer problems.

D.It helps slow the body down.

2.According to the passage, which of the following tells you need sleep?

A.You use up a lot of energy.

B.You enjoy daily activities.

C.Your body temperature falls.

D.You don't want to get up.

3.What does the underlined word "conserve" mean?

A.provide

B.move

C.save

D.spend

4.What is this passage mainly about?

A.Sleep is very important.

B.The brain needs enough sleep.

C.Good ways to sleep well.

D.People use energy when sleeping

 

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