【答案解析】根据联合国环境规划署最近的一次报告，如果汽车数量保持现在的增长速度，到2025年，汽车总数将超过10亿辆。现在，机动车每年排放9亿公吨的二氧化碳，约占二氧化碳总排放量的15%。更多的车辆将意味着更严重的全球变暖。同样，到2025年，世界三分之二的人口将在城市居住，因此交通拥挤和环境污染问题将日益突出，影响大多数人的生活。 [解析]
According to a recent report by the UNEP, if car numbers keep increasing at the present rate, there will be more than a billion on the road by 2025. Today, motor vehicles put out 900 million tones of carbon dioxide a year--about 15 percent of our total output. More vehicles will mean more global warming. Also by 2025, two-thirds of the world"s people will live in cities, so traffic jams and pollution will loom large in most people"s lives.

【答案解析】我们居住在一个物质的药用和社会使用泛滥的社会里：一片阿司匹林用来减轻头痛，一些葡萄酒用于交际，咖啡在早晨可以提神，何时这些社交上被接受而显然也是有益的物质使用变成滥用了呢?大多数物质过多摄入后会产生诸如中毒等的负面影响。对于某种物质的重复使用同样能导致上瘾或者是物质依赖性。依赖性首先表现为增加最大用量，后来，当物质不再提供的时候，会表现出断瘾反应。 [解析]
We live in a society in which the medicinal and social use of substances is pervasive: an aspirin to quiet a headache, some wine to be sociable, coffee to refresh oneself in the morning. When do these socially acceptable and apparently constructive uses of a substance become misuses? Most substances taken in excessively will produce negative effects such as poisoning. Repeated use of a substance can also lead to addiction or substance dependence. Dependence is marked first by an increased tolerance, and then by the appearance of withdrawal symptoms when the substance is discontinued.