题型:阅读选择 题类: 难易度:困难
上海市普陀区重点中学2024年中考英语模拟试题
Like visible light, UV rays are energy waves released by the sun, only they cannot been seen. Some exposure (暴露) to those waves can do a body good. For example, ultraviolet B (UV-B) rays tell human skin to make vitamin D. Too much exposure can be harmful, though. Overexposure to UV rays can cause DNA problems, opening the door for skin cancer.
Too much sun can also cause painful sunburns.
There are three different types of UV energy waves. They are UV-A, UV-B and UV-C rays. Each type moves at a different wavelength, with UV-A's being the longest. Rays of UV-C are considered especially harmful to human beings.
Fortunately, we have the ozone (臭氧) layer of the Earth's atmosphere. It blocks out nearly all of the UV-C rays and most of the UV-B ones.
The moon doesn't have much of an atmosphere, though. Back on the moon, things are more dangerous. Over the years, astronauts have planted six American flags on the moon. Some scientists think that powerful UV rays could have bleached all the colorful flags white by now. For this reason, the moon is a dangerous place to visit without protection. You might think that astronauts who visit the moon would come home with terrible sunburns. That didn'thappen to
Armstrong and his company. Neil Armstrong was a U. S. astronaut and the first person to walk on the moon. These astronauts all wore special spacesuits on their missions. Spacesuits were made with heavy fabrics that block out UV rays.
When Armstrong set foot on the lunar surface, he was wearing a see-through helmet (头盔) with sun shades that were made of ultraviolet-stabilized polycarbonate. It is a very tough plastic that protects astronauts' faces from UV rays. A
weaker material could put the space travelers at risk for "snow blindness" and other problems. Conditions like these arise when UV rays damage parts of the human eyes.
Sunscreen (防晒霜) defends us from the UV rays that do pass through the ozone layer. However, there's really no need for an astronaut to put on sunscreen. The risk of sunburn goes way down when astronauts are inside a spaceship. Inside
the International Space Station (ISS), for example, there is no need for special suits. Astronauts regularly do their work in nothing but common cotton shirts and pants. To protect them from sunburns, the ISS uses UV-blocking windows. So do most space exploration ships.
From small ants to big whales, almost all animals need to sleep. Some sleep a little. Some sleep a lot. And some have special ways to get their sleep.
Seabirds | Some seabirds spend most of their lives over the ocean. And they can sleep while they are flying. They can fly for many hours without moving their wings. |
Flamingos | A flamingo can sleep while standing on one leg. The standing leg always stays straight. The other leg stays close to its body. Its head rests on its back. |
Horses | Horses often sleep standing up. If a horse lies down, it needs a long time to get up. A horse can run from danger more quickly if it is already standing. And horses only need about three hours of sleep a day! |
Giraffes | Giraffes win the prize(奖) for sleeping the least. They sleep about 30 minutes a day, and 5 minutes at a time. They lie down when they sleep. They rest their heads on their bodies or on the ground. What a strange way of sleeping! |
Dolphins | A dolphin sleeps with just half its head at a time. The other half must stay awake(醒着的) to take in air and to watch for danger. Dolphin mothers and babies can go without sleep for as long as two months to stay safe. |
Everyone feels stress sometimes. You feel stress when you have a lot of work to do and not enough time. {#blank#}1{#/blank#} Sometimes, a little stress can be good. But usually, stress is bad.
{#blank#}2{#/blank#}. Stress can make it hard to sleep well. It can also make it difficult to finish school work. If you have a health problem, stress can make it work
There are some things you can do to feel less stress. {#blank#}3{#/blank#} Talking about stress can help you understand it. How can you take away the problem that is making you feel stress? {#blank#}4{#/blank#}
Exercise is also a good way to help with stress. Different exercises, like playing sports or walking, can help you feel better. {#blank#}5{#/blank#} Getting enough sleep, eating the right kinds of food, and having time to sit still are all important.
If you feel that you have too much stress, tell other people and get some help.
A.Sometimes, writing down the problem and writing ways to take it away can help. B.Make sure that you are taking care of yourself. C.You can also feel stress when you have problems. D.Too much stress can cause health problems. E.You can talk to your parents or a friend about your feelings. |
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