高中英语人教版（2019）选修三Unit 2 Healthy Lifestyle Learning about Language同步课时训练

—(figure) out whether this material breaks easily under high pressure.

Fat and shy, Ben Saunders was the last kid in his class picked for any sports team. "Football, tennis, cricket—anything with a round ball, I was useless," he says now with a laugh. But back then he was the one always made fun of in school gym classes in Devonshire, England.

It was a mountain bike he received for his 15th birthday that changed him. At first he went biking alone in a nearby forest. Then he began to ride the bike along with a runner friend. Gradually, Saunders set up his mind on building up his body, increasing his speed and strength. At the age of 18, he ran his first marathon.

The following year he met John Ridgway and was hired as an instructor at Ridgway's school of adventure in Scotland, where he learned about Ridgway's cold-water exploits. Greatly interested, Saunders read all he could about North Pole explorers and adventures, and then decided that this would be his future.

In 2001, after becoming a skillful skier, Saunders started his first long-distance expedition (探险) towards the North Pole. It took unbelievable energy. He suffered frostbite (冻疮), ran into a polar bear and pushed his body to the limit, pulling his supply-loaded sled (雪橇) up and over rocky mountains.

Saunders has since become the youngest person to ski alone to the North Pole, and he's skied more of the North Pole by himself than any other British man. His old playmates would not believe the change.

Saunders heads south from the coast of Antarctica to the South Pole and back, a 2,900-kilometre journey that has never been completed on skis.

There's nothing like a good night's sleep—but what does that really mean? It turns out that the answer depends not only on your age, but also on your lifestyle. Some people are productive and happy with fewer hours of sleep, while others need more. Still, experts can determine guidelines that work for most people. The National Sleep Foundation researched the topic and gave new recommendations. The foundation acknowledges that sleep needs will vary—lifestyle and stress should be taken into consideration—but their recommendations offer a general guideline. For example, teenagers need 8—10 hours' sleep every day.

To create the recommendations, some sleep and medical experts reviewed 312 articles from journals published during the last decade. This is the first time that a professional organisation has developed age-specific recommended sleep duration based on a systematic review of the world scientific literature.

A lack of sleep can be linked to weight gain, because that causes an increase in appetite, according to the foundation. It can also have serious consequences on the brain. People who do not get enough sleep are at increased risk of depression, and can endanger others. Those who become sleepy while driving, for example, risk both their lives and the lives of those around them.

Researchers also have found in the past that too much sleep can have negative effects. Reportedly, low socioeconomic status and depression are significantly associated with longer sleep. However, experts nowadays find that research on oversleeping is still unconvincing and needs more attention. Currently, there is no strong evidence that sleeping too much has health consequences. There is, however, laboratory evidence that short sleep duration of four to five hours has negative consequences. We need similar laboratory studies to determine whether long sleep duration results in physiological changes that could lead to disease before we make any recommendations against sleep extension.