We take showers and use the toilet every day to get rid of bodily waste. Our brains also need to take a bath every day. How can they do it?
A 2013 study found the answer. Researchers at the US University of Rochester studied the brains of mice and discovered that they cleaned themselves while the mice slept. A kind of fluid (液体) in the brain, called cerebral spinal fluid (CSF, 脑脊液), was found to increase dramatically (显著地) during sleep, washing away waste proteins that had been building up between brain cells in waking hours.
“This study shows that the brain has different functional states when asleep and when awake,” Maiken Nedergaard, the lead researcher, told NBC News. It also explains why we can’t seem to think clearly after a sleepless night while a good night’s sleep leaves us feeling sharp and refreshed.
Now a new study, published on Oct. 31 in Science, digs a little deeper into our brains’ self-cleaning procedure. Instead of mice, this time humans were the test subjects.
Researchers at Boston University, US, monitored the brainwaves of 13 healthy adults who were sleeping, using accelerated FMRI (核磁共振成像), which is capable of recording faster changes inside the brain than a regular FMRI machine. They found that every 20 seconds, blood flowed out of the brain, making room for a large amount of CSF to come in and “clean”. This cycle coincided with (与....一致) the rhythm of the brain’s slow waves—an electrical activity that happens when we’re in a deep sleep.
It’s still unknown how these brain activities are connected. But the mere fact that they are connected is exciting enough, since it allows researchers to piece together (拼凑出) possible new explanations for misunderstood diseases.
For example, slow-wave sleep has been proven to play a role in strengthening our memories. This may explain why people with Alzheimer (阿尔茨海默病) often have fewer and weaker slow brainwaves. Based on this new study, there could be one more explanation for diseased brains: They are not clean.
Nedergaard, leader of the 2013 study, is also excited about the new findings. “Maybe the most important take-home message is that sleep is a serious thing,” she told Scientific American. “You really need to sleep to keep a healthy brain because it links electrical activities to a practical ‘housekeeping’ function.”
1.What did the researchers find when they studied the brains of mice?
A.CSF in their brains decreased when the mice slept.
B.More waste proteins were produced in their brains during sleep.
C.CSF carried away waste proteins in their brains during sleep.
D.The more CSF was in their brains, the fewer proteins were there.
2.What did the researchers discover when they monitored human brainwaves?
A.It took 20 seconds for CSF to clean brains.
B.Brains were “cleaned” when blood flowed out.
C.The rhythm of the brain was slower than that of CSF.
D.The brains worked more slowly when asleep.
3.What are the last three paragraphs mainly about?
A.The significance of the research.
B.The features of slow-wave sleep.
C.The importance of having a good sleep.
D.The connections between these brain activities.
阅读下面短文，根据所给情节进行续写，使之构成一个完整的故事。
Many years ago, when I was fresh out of school and working in Denver, I was driving to my parents' home in Missouri for Christmas. I stopped al a gas station about 50 miles away from
Oklahoma City, where I was planning to stop and visit a friend. While I was standing in line at the cash register(收银台）,I said hello to an older couple who were also paying for gas.
I took off, but had gone only a few miles when black smoke poured from the back of my car. I stopped and wondered what I should do. A car pulled up behind me. It was the couple I had spoken to at the gas station. They said they would lake me to my friend's. We chatted on the way to the city, and I got out of the car, the husband gave me his business card.
I wrote him and his wife a thank-you note for helping me. Soon afterwards, I received a Christmas present from them, Their note that came with it said helping me had made their holidays meaningful.
Years later, I drove to a meeting in a nearby town in the morning. In late afternoon I returned to my car and found that I'd left the lights on all day, and the battery (电池）was dead. Then I noticed that the Friendly Ford dealership-a shop selling cars-was right next door. I walked over and found two salesmen in the showroom.
注意：
1, 所续写短文的词数应为150左右；
2. 至少使用5个短文中标有下划线的关键词语；
3. 续写部分分为两段，每段的开头语已为你写好；
4. 续写完成后，请用下划线标出你所使用的关键词语。
Paragraph 1:
I entered the shop, and one of the salesmen came to me.
Paragraph 2:
After a while, they quickly drove a pickup truck to my car and started it.
请认真阅读下列各小题，并根据上下文语境和所给首字母或中文的提示，写出下列各句空格中的单词，注意保持语义和形式的一致。请将答案的完整形式写在答题卡上相应题号的横线上。
1.—Have you seen a lady's handbag on the__________（柜台）? I left it here a moment ago.
—What color is the bag? We found one really.
2.Only when women are enabled to become strong will our families, our economies, and our societies reach their fullest______________（潜能）。
3.According to the central bank, the new edition bills will__________（流通） in parallel with previous editions and will have the same face value.
4.About online education, in my opinion, there are many________（有效） ways of using videos in language teaching.
5.—A little disabled dog was found___________（抛弃） on the steps of the pet clinic.
—How cruel its owner is!
6.In view of lacking preparations for the competition and not wanting to lose face, Johnson e________ decided to drop out.
7.The boat whistled past, making the water in the river s___________ open.
8.It is generally a____________ that Internet addiction will have a disturbing effect on people's health and social relationships.
9.When the stranger was dragging him away, the baby reached out his hands in d__________ want of his mother.
10.—George, get down to doing your homework, OK?
—Oh, Mom. You know that I can't r_____________ watching TV.
阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。
High on the Qinghai-Tibet Plateau 1.(lie) China’s “water tower” Sanjiangyuan. It is home to the headwaters of China’s three rivers: the Yellow River, Yangtze River, and Lancang(Mekong) River. It is the three rivers 2. provide water for about half the population of China. However, human activities are putting this ecosystem 3. risk. Hopefully, though, we can repair this damage. In 2016, the Chinese government established Sanjiangyuan National Park in Qinghai province. The park, 4.(schedule) to open in 2020, has increased the area’s green coverage and attracted more wildlife. The local government has also made great effort to improve biological diversity. The success of Sanjiangyuan will mark the start of a 5.(green) future. With Sanjangyuan 6.(take) the lead, nine other regions in China 7.(choose) by a field conservation station to carry out projects over the past three years, 8. will form a national park system together. The idea of a national park system is still new in China, but9.(it) realization is urgent. After all, building an ecological civilization bears great 10.(important) in the development and progress of human civilization.
One morning our new neighbor saw my grandfather planting two rare tree saplings(树苗）in our garden. And he also planted the same kind of tree saplings in his garden. My grandfather gave________enough amount of water to his plants and didn't always give them full ______while our neighbor gave a lot of water to his plants and ______them too well. My grandfather's plants were simple but looked good, _______our neighbor's plants were much fuller and greener.
Normally, in summer, we have strong thunderstorms called "Kalboishakhi" which can bring great damage to life and _______. After a "Kalboishakhi", my grandparents and I came out to________the damage to our garden and saw the neighbor was in his garden, too, but look ______as his plants were uprooted. Our plants weren't damaged and were standing ______ on the ground, our neighbor was______ to see this, and he came up to my grandfather and said with______, I actually looked after my plants better than you did for yours. ______, my trees came off from the roots, but yours didn't. How is this_______?"
My grandfather smiled and said, "You gave your plants more attention and water, so they didn’t have the ______to work themselves for anything. I gave them just the ample amount of and manure (肥料），letting their_______ search for more;thus they went deeper and made their position stronger, That is why my plants________ With an expression of deep_______ our neighbour nodded_______It made me realize then that though my grandfather was ______with me on many occasions even during our vacations with his do's and don'ts, I became aware that anything ______got or can go off that much more easily and we will not ______the hard work it takes earn those things. "
1.A.mainly B.nearly C.barely D.exactly
2.A.hope B.support C.time D.attention
3.A.dealt with B.looked after C.brought up D.waited on
4.A.and B.while C.so D.or
5.A.animals B.land C.environment D.possessions
6.A.predict B.analyze C.check D.confirm
7.A.tired B.upset C.bored D.ashamed
8.A.firm B.still C.bent D.abnormal
9.A.disappointed B.relieved C.frightened D.surprised
10.A.anger B.sorrow C.embarrassment D.anxiety
11.A.Anyway B.However C.Otherwise D.Therefore
12.A.possible B.exciting C.alike D.suitable
13.A.reason B.need C.chance D.power
14.A.branches B.trunks C.leaves D.roots
15.A.survived B.twisted C.spread D.delayed
16.A.admiration B.doubt C.regret D.sadness
17.A.public B.peace C.approval D.turn
18.A.strict B.annoyed C.patient D.content
19.A.occasionally B.mistakenly C.secretly D.easily
20.A.understand B.accelerate C.oppose D.undertake
When you think about a deadly animal, you may think of a shark, a lion, or even an elephant. However, the truth is that the deadliest animal in the world is much smaller and more annoying. 1.And it feeds on human blood, transporting numerous diseases from one person to the next. Figure it out, yet? Yes, it's the mosquito.
The numbers don't lie: According to the World Health Organization, more than 725, 000 people worldwide are killed by mosquito-borne diseases each year. These diseases include malaria(疟疾） dengue fever, yellow fever, and encephalitis, 2."Being able to adapt easily to new environments is one of the reasons why mosquitoes are the most deadly, "Bums Blackwell, an expert in pest control said.
3.Mosquitoes have learned to lay eggs in as little as a few small drops of water and each female mosquito can lay between 50 and 500 eggs once. Their populations also reach the highest point at different times in different areas all over the world, making it nearly impossible to avoid being bitten4.
In areas where there' re too many mosquitoes, local authorities try to control the population through routine pesticide(杀虫剂）applications. "We should protect ourselves by avoiding places where there is too much water, "said Bernard Cohen, MD, a professor at the Johns Hopkins University School of Medicine. 5. Wear bug repellent(驱虫剂）that contains DEET(up to 30 percent)when heading outdoors, and reapply it about every four hours.
A.Most of the diseases can be cured in a short time.
B.There are more than 100 varieties of this thing on earth.
C.He also stresses that a little protection will go a long way.
D.And every bite increases the risk of getting a serious disease.
E.Mosquitoes take much interest in getting in touch with children.
F.Malaria is the most horrible, killing at least 600, 000 people a year.
G.Another reason the insects are so deadly is that they produce quickly.
