题目内容
A．Half a year.B．Four or five years.C．Three years.D．One year.
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A．Attracting mates.B．Staking their territories.C．Hearing each other.D．Sleeping.
For millions of years before the appearance of the electric light, shift work, all night cable TV and the Internet, Earth's creatures evolved on a planet with predictable and reassuring 24-hour rhythms. Our biological clocks are set for this daily cycle. Simply put, our bodies want to sleep at night and be awake during the day. Most women and men need between eight and eight and a half hours of sleep a night to function properly throughout their lives. (Contrary to popular belief, humans don't need less sleep as they age.)
But on average, Americans sleep only about seven and a half hours per night, a marked drop from the nine hours day averaged in 1910. What's worse, nearly one third of all Americans get less than six hours of sleep on a typical work night. For most people, that's not nearly enough.
Finding ways to get more and better sleep can be a challenge. Scientists have identified more than 80 different sleep disorders. Some sleeping disorders are generic. But many problems are caused by staying up late and sleeping in, by traveling frequently between time zones or by working nights. Dr. James. F. Jones at National Jewish Medical and Research Center in Denver says that sleep disorders are often diagnosed as other discomforts. About one third of the patients who referred to him with possible chronic fatigue syndrome actually have treatable sleep disorders. "Before we do anything else, we look at their sleep," Jones says.
Sleep experts say that most people would benefit from a good look at their sleep patterns, "My motto (座右铭) is 'sleep defensively'," says Mary Carskadon of Brown University. She says people need to carve out sufficient time to sleep, even if it means giving up other things. Sleep routines—like going to bed and getting up at the same time every day—are important. Pre-bedtime activities also make a difference. As with Elsneer, who used to suffer from sleeplessness, a few lifestyle. changes—avoiding stimulants and late meals, no exercising before bedtime, but relaxing with a hot bath—yield better sleep.
What is TRUE of human sleep？
Section B
Directions: In this section, you will hear 3 short passages. At the end of each passage, you will hear some questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer from the four choices marked A, B, C and D.
听力原文： The world has become a noisier place, say experts at the Library of Natural Sounds in Ithaca, New York. The library has the world's largest collection of natural sound recordings---including the sound of birds, frogs, and mammals. The recordings are used for scientific study, field guides, and even some movie background sounds. Finding quiet areas for recording is becoming difficult, says Greg Budney, head of the library. Even in sparsely populated areas, animal sounds can be submerged by moving trucks, highway traffic, or aircraft. Obtaining a clean recording of an animal may take days or even years, and a habitat recording of all the species in an area is virtually impossible. Animals are having trouble heating each other in loud noises as well. A report from the British Ecological Society claims that, because of noise from nearby British roadways, some birds are having trouble attracting mates and staking out their territories.
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中国共产党第一次提出要“解决农民的困苦,根本是要实行‘耕地农有’的办法,就是谁耕种的田地归谁自己所有的”主张是在:
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