Unit 3 Under the sea grammar课时作业
第一节 阅读理解
A so-called “smart drug” intended to improve cognitive(认知的) performance also seems to protect the brain from altitude sickness.
Even more people are visiting high-altitude sites for work, sport, religious pilgrimages and military tasks. But even the fittest among us suffer in thin air:the lower oxygen content at the altitude can lead to cognitive effects, including memory loss and attention difficulties.
There’s little you can do to prevent these symptoms other than acclimatize—but this takes time and doesn’t always work. A drug called oxiracetam might be the answer.
ShengLi Hu at the Third Military Medical University, Chongqing, China and her colleagues studied the performance of male military personnel at altitude. All lived in towns around 1,800 meters above sea level. During the study, they spent eight days at this altitude and then climbed for three days to reach 4,000 meters, where they stayed for up to a month.
Twenty participants took oxiracetam three times a day for the first 15 days of the study, while another 20 received no intervention. The man did tests of attention and memory at the start and end of the study and 20 days in, by which time they had been at 4,000 meters for nine days.
While all the participants experienced a drop in cognitive ability at 4,000 meters, those who took oxiracetam showed a much smaller decline than the control group.
Blood flow measurements indicated that at high altitude, parts of the brain’s cerebral circulatory system contracted and dilated (扩张) in a way that promoted blood flow to the brain stem. This isn’t surprising, since the brain stem plays a critical role in the maintenance of basic vital signs.
The team also found that the brain stem received blood at the expense of areas responsible for more advanced cognitive functions. But in people who took oxiracetam, more arteries dilated, so blood flow throughout the brain rose. This may
be how the drug seems to lessen cognitive problems linked with low oxygen.
It isn’t yet known whether diverting blood in this way could have negative effects in the long run.
“The results are striking and imply that oxiracetam may be beneficial for helping to relieve cognitive deficits caused by the altitude,” says Timothy Hales at the University of Dundee, the UK.
“Oxiracetam is not licensed for medical use globally, but it is known to be a mild stimulant,” says Hales. “Coca leaves have been used by native Andeans for centuries to overcome altitude sickness and this is attributed to their modest cocaine content. So perhaps it is not surprising that benefit can be derived from another, though mild, stimulant.”
1.The underlined word “acclimatize” in Paragraph 3 is closest in meaning to .
A.adapt
B.interact
C.exist
D.object
2.What does the experiment done in China reveal?
A.The higher altitude you are at, the slower your brain will be. B.At 4,000 meters, the two subject groups show no difference. C.Memory tests are beneficial to relieving attention difficulties. D.The“smart drug” largely counters negative effects of altitude sickness. 3.According to the passage, the root cause of the cognitive effects lies in . A.physical tiredness B.low oxygen content C.cognitive training D.extreme high altitudes
4. What is the best title for the passage?
A.Fight high anxiety B.Oxiracetam—a magic drug C.Keep sharp at the altitude D.Problems on high-altitude sites 第二节 任务型阅读
请认真阅读下列短文，并根据所读内容在文章后表格中的空格里填入一个最
恰当的单词。
注意：请将答案写在答题卡上相应题号的横线上。每个空格只填1个单词。 Anyone who’s ever made room for a big milestone of adult life----a job, a marriage, a move----has likely shoved a friendship to the side. After all, there is no contract locking us to the other person, as in marriage, and there are no blood bonds, as in family. We choose our friends, and our friends choose us. That’s a really distinctive attribute of friendships.
But modern life can become so busy that people forget to keep choosing each other. That’s when friendships fade, and there’s reason to believe it’s happening more than ever. Loneliness is on the rise, and feeling lonely has been found to increase a person’s risk of dying early by 26%----and to be even worse for the body than obesity and air pollution. Loneliness damages health in many ways, particularly because it removes the safety net of social support. “When we perceive our world as threatening, that can be associated with an increase in heart rate and blood pressure.”
The solution is simple: friendship. It helps protect the brain and body from stress, anxiety and depression. “Being around trusted others, in essence, signals safety and security,” says Holt-Lunstad. A study last year found that friendships are especially beneficial later in life. Having supportive friends in old age is a stronger predictor of well-being than family ties ----suggesting that the friends you pick may be at least as important as the family you’re born into.
Easy as the fix may sound, it can be difficult to keep and make friends as an adult. But research suggests that you only need between four and five close pals. If you’ve ever had a good one, you know hat you’re looking for. “The expectations of friends, once you have a mature understanding of friendship, don’t really change across the life course,” Rawlins says. “People want their close friends to be someone they can talk to and someone they can depend upon.”
If you’re trying to fill a dried-up friendship pool, start by looking inward. Think back to how you met some of your very favorite friends. Volunteering on a political campaign or in a favorite spin class? Playing in a band? “Friendships are always about something,” says Rawlins. Common passions help people bond at a personal level,