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（B）
It is natural that children are curious about the world around them. For example, they want to know how their hearts beat. They want to know why the ocean water tastes salty.
As children grow up, they become curious about different kinds of things. When they are babies, they are interested in the parts of their bodies and in the smiles of their mothers. Then they become interested in the physical world around them: the plants, the animals, and the sky. Later, they become interested in the things that people have made: wheels, bicycles, cars. And when they are adults, their curiosity continues. Sometimes this curiosity leads to a career in science.
Scientists spend their lives trying to find out about the world. Those who work with the earth sciences study the earth, the oceans, and the skies. Other scientists who study living things work with the biological sciences. A third group of scientists study the physical sciences, e.g., physics, chemistry.
These scientists have already discovered a lot about our world. For example, they tell us why your heart beats fast when you run. They say that when you are quiet, your heart normally beats sixty-five or seventy-five times a minute. Your heart is like a pump that pumps blood to all parts of the body. The blood carries oxygen and nutrition. When you run, your muscles work very hard and use the nutrition that the blood carries to them. The muscles need oxygen, too. So your brain sends a signal to the heart. The signal means that the muscles need more nutrition and oxygen. Then the heart beats fast and sends blood quickly to the muscles. It may beat 90 to 140 times a minute.
Of course, scientists cannot answer all of our questions. If we ask “Why does the ocean water taste salty?” scientists will say that the salt comes from rocks. When a rock gets very hot or very cold, it cracks. Rain falls into cracks. The rain then carries the salt into the earth and into the rivers. The rivers carry the salt into the ocean. But then we ask, “What happens to the salt in the ocean? The ocean does not get saltier every year.” Scientists are not sure about the answer to this question.
We know a lot about our world, but there are still many answers that we do not have, and we are curious.
46. Which of the following statements is true?
A. People are curious in the same way.
B. People in different countries are interested in different things.
C. Men and women are curious about different things.
D. People of different ages are interested in different things.
47. Scientists who work with the biological sciences study ______________________.
A. the earth, the oceans and the sky B. ocean water
C. plants and animals D. man-made things
48. When you run, your muscles need ______________________________.
A. more nutrition and oxygen B. more signals
C. more salt D. water
49. A rock cracks ________________________________________.
A. in wet regions B. in dry regions
C. at very high or very low temperatures D. when salty water falls in
50. People are always curious because _________________________.
A. they cannot explain many things B. they know nothing about the world
C. they know little about the world D. they want to be scientists
查看习题详情和答案>>How would you like to brush a crocodile’s teeth? Or give a shark a bath? Cats are well-known for the way they keep themselves clean by licking （舔）, but other animals have their own ways to stay clean as well. And tidiness can be important for their survival. Even cockroaches （蟑螂） have to keep their feelers clean to help them into food.
Many animals in the wild, such as deer, wolves and bears, have an automatic cleaning system. Insects like to attach themselves to animals to feed on the skin or blood. These parasites （寄生虫） can be unhealthy. But their “host” animals are constantly dropping skin and fur by a natural process. They also like to rub up against trees or rocks to comfort themselves, and this removes additional skin and fur. Along with old fur goes the dirt and parasites living in the fur. While these animals may sometimes take a bath when they enter or cross a river or lake, they don’t need the water to stay clean. They don’t get sweaty, because they don’t have sweat glands （汗腺） all over their bodies the way people do. Growing new skin and fur is enough to keep them clean.
Some animals and birds use dust to get clean. Chinchillas, a kind of small animal that lives in the mountains of South America, have a very fine fur. （They are raised for their fur, in fact.） If they took water baths, they might get too cold. So, instead, they roll around in fine dust, raising quite a cloud as they “bathe”. The dust helps to keep their fur and skin dry. This protects them from bacteria and parasites that enjoy warm and wet places. And the fine dust doesn’t stick in their fur for long. It falls off or blows away.
As for lions and tigers, their rough tongues act like combs and can remove dirt and loose fur. Why is it important for them to stay clean and smooth? It helps them stay cool in very hot summer or feel warm in cold winter.
64. What’s the main idea of this passage?
A. Animals enjoy living in a clean environment.
B. Animals fight against parasites in different ways.
C. Unlike people, animals hate staying in water.
D. For animals, cleanliness is a survival skill.
65. According to the passage, such animals as deer, wolves and bears clean themselves by .
A. living with parasites
B. replacing their skin and fur naturally
C. climbing trees or rocks
D. having a bath in a river or lake
66. It can be inferred from the passage that the way some animals stay clean .
A. is decided by their physical conditions
B. is better than the way people do
C. keeps them away from parasites all the time
D. helps them survive any danger in the wild
查看习题详情和答案>>After having been successful in his career, a man felt a strong desire to repay his mother for all that she had done for him. Although she 1 to ask for anything, he continued to persist (坚持). To put a(n) 2 to the discussion, she said, “All right. If you must, then tonight you sleep on my bed with me, just as you 3 when you were a baby. ” He said, “That’s a 4 thing to ask for, but if it 5 you, I will.”
After 6 , the man slept with his mother. As soon as he fell asleep, the mother got up and 7 a mug (有柄的大杯) of water on his side. Feeling 8 by the wetness under him, he 9 to the other side of the bed. As he 10 , his mother poured 11 mug of water on the other side. In his sleep he tried to find 12 towards the foot of the bed. Some time later he woke up feeling that this part of the bed was 13 , too. He got up and saw his mother, 14 the mug in her hand. He asked, “What are you doing, mother? Why don’t you 15 me sleep? How do you expect me to sleep on a wet bed?”
Mother said, “I slept with you, when you 16 the bed in the night. I 17 your nappy (尿布) and moved you to the dry part of the bed, 18 I slept on the wet side. You wanted to 19 me. Can you sleep here with me 20 for one night on a damp bed? If you can, I’ll take it that you have repaid me.”
1．A．demanded B．refused C．prepared D．advised
2．A．reply B．conclusion C．end D．entrance
3．A．used to B．would to C．would like to D．ought to
4．A．right B．proper C．funny D．strange
5．A．comforts B．pleases C．encourages D．answers
6．A．supper B．breakfast C．work D．lunch
7．A．drank B．poured C．heated D．placed
8．A．disturbed B．interrupted C．disappointed D．annoying
9．A．stayed away B．walked away C．moved away D．turned away
10．A．lay down B．broke down C．sat down D．settled down
11．A．other B．any C．another D．one
12．A．cloth B．peace C．space D．water
13．A．cold B．damp C．hard D．hot
14．A．under B．with C．on D．beside
15．A．hope B．ask C．cause D．let
16．A．wetted B．poured C．dirtied D．watered
17．A．bought B．dried C．cleaned D．changed
18．A．when B．while C．as D．so
19．A．repay B．thank C．satisfy D．understand
20．A．never B．still C．even D．ever
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