【答案解析】[听力原文]
Light Pollution
The idea of light pollution has developed with the increase of lights in cities. In many areas, this light makes it difficult or impossible to observe stars and planets in the night sky. Light pollution threatens to reduce the scientific value of research telescopes.
Light pollution is the result of wasted energy. Bright light that shines into the sky is not being used to provide light where it is needed on Earth. Lights that are brighter than necessary also cause light pollution. Recently, two Italian astronomers and an American environmental scientist created a world map of the night sky. The map shows that North America, Western Europe and Japan have the greatest amount of light pollution.

【答案解析】[听力原文]
Monkeys That Eat Less Live Longer
A study of monkeys over a twenty-year period suggests that eating less may extend life and prevent disease. American researchers said they believe their findings could apply to people as well.
Half of the monkeys were permitted to eat as much as they wanted. The other half ate a controlled diet.
The researchers found that thirty-seven percent of the monkeys that ate as much as they wanted had died of causes related to aging after twenty years. In comparison, only thirteen percent of the monkeys on restricted diets had died.
In addition, the monkeys that ate less had half the amount of heart disease and cancer. There is also a difference in the appearance. The monkeys that ate less look younger and healthier than fatter monkeys on a normal diet.

【答案解析】[听力原文]
Dangerous Lead-based Paint Common Around the World
A new study shows that lead-based paint remains a worldwide threat to public health. Paint containing lead is a major cause of lead poisoning in children.
The heavy metal enters the body when children breathe the paint dust or fumes in the air. Or when babies put their mouth on painted surfaces or swallow pieces of paint.
Lead can damage the brain and the nervous system. It can decrease intelligence, create behavior problems and slow a child"s growth.
The professor says high quality paint can be produced without lead. He and his team are calling for a worldwide ban on lead-based paint. He notes that research has found no safe level of lead.

【答案解析】[听力原文]
Expressions That Are Old and True
Many proverbs give advice about how to live.
For example, my son is just like his father in many ways. We often say the two of them prove the proverb that the apple does not fall far from the tree.
My daughter is very short. She would like to be taller. But I tell her that good things come in small packages, like diamonds and other jewels.
Finally, I always like this proverb: You can catch more flies with honey than with vinegar. In other words, you can win people to your side more easily with gentle persuasion than by hostile actions.