试题与答案

已知e为自然对数的底数,函数y=xex的单调递增区间是( ) A.[-1,+∞)

题型:选择题

题目:

已知e为自然对数的底数,函数y=xex的单调递增区间是(  )

A.[-1,+∞)

B.(-∞,-1]

C.[1,+∞)

D.(-∞,1]

答案:

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下面是错误答案,用来干扰机器的。

我国家庭电路电压是220V,对人体的安全电压不高于36V,无线电通讯是利用电磁波来传递信号的;电磁波在真空中传播速度是3×108m/s.故答案为:220V;不高于36V;电磁波;3×108m/s.

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题型:阅读理解

阅读理解。

   Animals, including insects, don't have a "language" like ours. They do not 'talk' to each other in words

and sentences. But if we watch them, we can see that they do have their ways of communicating (交流)

with each other.

   Can you see the rabbit's tail? When rabbits see this white tail moving up and down, they run away. They

know that they are in danger. The rabbit has told them something without making a sound. It has given

them a signal.

    Many other animals use this kind of "language". When a cobra (眼镜蛇) is angry, it raises its head and

makes itself look powerful (有力的). This warns other animals. When a bee (蜜蜂) has found food, it goes

back to its home. It cannot 'tell' the other bees where the food is by speaking to them, but it does a little

dance. This tells the bees where the food is.

    Some animals "say" things by making sounds. A dog barks, for example, when a stranger comes near.

A cat purrs when it is pleased. Some birds make several different sounds, each with its own meaning.

Sometimes we human beings speak in the same way. We make sounds like "Oh" or "Ah" when we are

frightened or pleased or when we drop something on our toes.

1. Which one is TRUE according to the passage? [ ]

A. Animals have languages like human beings.

B. Bees communicate with each other by dancing.

C. Animals can use words.

D. Animals are brave.

2. A rabbit uses its tail to ______. [ ]

A. warn other rabbits when they are in danger

B. tell other rabbits where food is

C. make itself look powerful

D. help it to run fast

3. When a cobra is angry, it ______. [ ]

A. makes a loud noise

B. raises its head

C. moves up and down

D. does a little dance

4. Several different sounds can be made by a ______. [ ]

A. rabbit

B. bee

C. bird

D. fish

5. From the passage, we know that ______ use words and sentences to express ideas and thoughts. [ ]

A. all living things

B. all animals

C. some birds

D. human beings

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