Going to the ballpark, visiting friends an

题型:问答题

问题:

Going to the ballpark, visiting friends and playing bingo are simple diversions for many of us. But for the elderly, these social pastimes may play a critical role in preserving their physical and mental health.

(46) In fact, a new study suggests that the less time older people spend engaged in social activity, the faster their motor function tends to decline. "Everybody in their 60s, 70s and 80s is walking more slowly than they did when they were 25," says Dr. Aron Buchman, a neurologist at the Rush University Medical Center in Chicago and leading author of the study, which was published in the June 22nd issue of the Archives of Internal Medicine. (47) "Our study shows the connection between social activity and motor function--and opens up a whole new universe of how we might intervene. "

(48) An increasing body of evidence has suggested that participating in mentally stimulating activity, socializing frequently and exercising may help protect against age-related decline-at least cognitive decline. As early as 1995, neuroscientist Carl Cotman, who studies aging and dementia at the University of California at Irvine, published a paper in Nature showing that physical exercise produces a protein that helps keep neurons from dying and spurs the formation of new neural connections in the brain. (49) More recently, Cotman demonstrated in studies of elderly dogs and mice that enriching their social environment is associated with improvement in brain function.

Researchers are also finding that social activity may be linked to the same protective effect in people. A recent study of 2 500 adults ages 70 to 79, published in the journal Neurology, found that those who were able to stay mentally sharp were also those who exercised once a week or more, had at least a ninth grade literacy level and were socially active.

While further research needs to be done to establish the exact impact of social activity and exercise on specific age-related declines (50) it’s likely that a reduction in social activity may simply be a symptom of physical decline, since people may naturally withdraw from social engagement as they lose motor skills-most researchers would agree that it is not unreasonable to encourage seniors to get out there more. Only 10% of people over 65 get the recommended amount of exercise (at least 2. 5 to 5 hours a week), and given that seniors already tend to be more socially isolated than younger adults, it’s difficult to motivate them to become more active. "If you are alone, you are less likely to follow recommendations," notes Verghese. It might help, though, if you visit Grandma more often and let her know that a regular pastime may just help her stay fitter and sharper longer.

(50) it’s likely that a reduction in social activity may simply be a symptom of physical decline, since people may naturally withdraw from social engagement as they lose motor skills

考点:普通考研考研数学(三)考研数学三
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Passage Two

Whales

Whales are aquatic mammals belonging to order CetaceA.A few species live in fresh water, but most species live in the seA.They have a streamlined shape and a powerful tail to drive them forwarD.With its two large horizontal fins or flukes, the tail produces the driving force by beating ply up and down. Flippers at the front are used for steering and balance. The hind limbs of whales have completely disappeared, apart from a few small bones inside the body. Body hair has also disappeared, giving whales a smoother outline and less resistance to water.Instead of hair, whales are insulated by a thick layer of fat, or blubber, under the skin. The blubber may be as much as 61 cm thick on some parts of the body. Besides protecting the animal against the cold, the blubber is an important food reserve.
Most of the best-known whales large creatures.For example, the blue whale reaches a length of more than 30 m.However, many whales, such as dolphins and porpoises, are small.Some are only 1.5 to 1.8 m long.
Whales live entirely in water.Sometimes, whales are stranded on the shore.Although they are air-breathing animals, they soon die because their great weight keeps them from expanding (opening out) the chest cavity.They can breathe easily when afloat, because the water supports most of their weight.
The bottle-nosed whale has been known to stay under water for about two hours.The sperm whale can dive down to depths of 500 fathoms.Such long and deep dives are unusual.Most dives last between 10 and 30 minutes.Whales have special mechanisms that help them to stay under water.When they breathe, they renew about nine-tenths of the air in their lungs.When human beings breathe in, only about one-fourth of the air is renewed.Whales therefore have a fairly large supply of fresh air to start with.They also have an additional oxygen supply in the muscles, where air is loosely held in combination with a pigment called myohaemoglobin.Another thing that helps whales hold their breath for long periods of time is their low sensitivity to carbon dioxide in the blood.(It is the carbon dioxide building up in human blood that affects the brain and makes the human being take another breath.)
When a whale surfaces to renew its air supply, it needs only to push the top of its snout out of the water.This is because the nostril or blowhole is at the top of the heaD.The expelled air is forced out ply to form the spout or blow.
Living whales are divided into two groups—tooth whales and whalebone whales.Tooth whales, which include most species, generally have many conical teeth and eat mainly squids and fishes.The killer whale feeds on seals.One African river dolphin feeds mostly on plants.Other tooth whales include the narwhal and the sperm whale.
Whalebone whales have no teeth.Their mouths contain huge comblike fringes of baleen or whalebone.This horny substance is usually black.All whalebone whales feed by straining small animals from the water.The mouth is filled with water and the water is then forced out through the fringes by the tongue.The animals caught in the baleen are swept into the stomach by the tongue. All whalebone whales are large animals, which are usually found in cold seas.They include the blue whales, the right whales, and the rorquals.
The future of many of the larger kinds of whales is uncertain. Whalers have killed so many blue, bowhead, humpback, and right whales that those species are threatened with extinction. Overhunting has also greatly reduced the number of fin and sei whales.Also, if the human population does not stop increasing, people may have to compete with whales for food in the seA.Some nations have begun fishing for krill.Krill is the chief food of whales in Antarctic waters.

We can learn from the passage all of the following about whales except that______.

A.their blubber performs two important functions

B.they vary greatly in size

C.overhunting places some of their species in danger of extinction

D.they struggle hard to compete with humans for food in the sea

题型:问答题

划拨国有建设用地使用权抵押需要订立抵押合同,并办理抵押登记,《担保法》规定()。

A.土地抵押是实务抵押

B.当事人不办理登记的,不得对抗第三人

C.抵押权的客体是法律允许转让的土地所有权

D.抵押权的客体是法律允许转让的土地凭借权

题型:问答题

作为滴丸剂的机制应具有良好的

A.表面活性
B.表面稳定性
C.化学活性
D.化学惰性
E.物理稳定性

题型:问答题

码分多址是一种利用()所形成的不同码序列实现的多址方式。

A、扩频技术

B、调制技术

C、编码技术

D、均衡技术

题型:问答题

张某,患肛周脓肿,行脓肿切开引流术,正确的皮肤消毒方法是()。

A.由手术区中心部向四周涂擦

B.由四周向中心区涂擦

C.已接触污染部位的消毒纱布球可反复消毒用

D.消毒范围为切口周围10cm区域

E.延长切口时,消毒范围不必再扩大

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