12.人類對環境的破壞 Ⅰ
段落大意：人類改變了生物圈的構成，打破了地球熱量平衡。
For the last 10,000.years, the earth’s climate has been extraordinarily beneficial to mankind. Humans have prospered tremendously （極大地） well under a benign（宜人的） atmosphere. Today, however, major changes are taking place. People are conducting an inadvertent（因疏忽造成的） global experiment by changing the face of the entire planet. We are destroying the ozone layer （臭氧層）, which allows life to exist on the earth’s surface. All of these activities are unfavorably altering （改變） the composition of the biosphere （生物圈） and the earth’s heat balance.
13.人類對環境的破壞 Ⅱ
段落大意：人類造成氣溫升高，改變了地球大氣的化學成分。
According to the National Academy of Sciences, global warming over the past century has caused a rise in earth’s surface temperature of about 1.degree Fahrenheit （華氏攝氏度）. There is an evidence to substantiate （證實） attribution （歸因） of the increased rate of this warming phenomenon over the past 50.years to human activities. Human activities have altered the chemical composition of earth’s atmosphere through the increase of greenhouse gases, chiefly carbon dioxide, methane, and nitrous oxide.
14.溫室效應
段落大意：溫室效應產生的原因及對地球的影響。
Global warming is sometimes referred to as the greenhouse effect. The greenhouse effect is the absorption of energy radiated from the earth’s surface by carbon dioxide and other gases in the atmosphere, causing the atmosphere to become warmer. The greenhouse effect is what is causing the temperature on the earth to rise, and creating many problems that will begin to occur in the coming decades.
15.全球變暖的原理
段落大意：溫室氣體吸收的光線對地球溫度的影響。
The greenhouse effect and global warming are issues that have been talked about by geologists all the time. The greenhouse effect is a natural process that keeps the earth at temperatures that are livable. Energy from the sun warms the earth when its heat rays （光線） are absorbed by greenhouse gases and become trapped in the atmosphere. Some of the most common greenhouse gases are water vapor, carbon dioxide, and methane. If there were no greenhouse gases, very few rays would be absorbed and the earth would be extremely cold. When too many rays are absorbed, the earth’s atmosphere starts to warm, which leads to global warming.
16.全球變暖的影響
段落大意：全球變暖會給地球上的一切東西帶來影響，其中消極的影響要多於積極的影響。
The effects of global warming touch everything on this planet, including humans, animals, plants, ocean, landmass, and atmosphere, etc. The numerous effects of global warming are mixes of “good”and “bad”results, depending on how your definition of “good”results and “bad”results are. A “good”effect, a person could say, would be for regions with normally cold temperatures to have warmer temperatures. However, there are more “bad”effects that seem to outweigh the “good”ones. Some of the effects would include increases of flooding, severe storms, and rising sea-levels. One major consequence would be an increase of temperature globally. This would lead to a chain reaction that would change precipitation （降雨量） within many ecosystems, which could cause a possible alteration（改變） in migration routes of various animals or produce permanent damage to creatures and their habitats（棲息地）, or worse, result in extinction of animals that cannot stand the change.
17.人類活動與環境保護
段落大意：人類活動威脅著地球，我們應該加強環保意識。
In the recent years there has been a significant rise in people’s concern for the environment. We all affect the natural environment, but we are often unaware of how much we affect it. The earth is an integrated system and there is no part of the earth we can say is not affected by our actions. Our actions are now threatening the health of our planet, the land we live in and work on, the water supply, the ozone layer, the animal species as well as the health of our human beings. Some people may question, “The problem is too great and what can we do now?”Well, we can reflect on our behavior and believe that we can make a difference.
18.塑料與水汙染
段落大意：造成水汙染的原因有很多，其中塑料廢棄物是主要原因。
Water pollution has affected many people and animals. Water pollution is the disposal （處理） of garbage into streams, rivers and oceans. Some of the water pollution is from littering, some is done by chemical leaks, and others by ships. There are many causes for water pollution. The main one is plastics. The reason for that is that plastics take four hundred and fifty years to decompose （分解） in water. Many companies use plastics and people throw it in waterways （水路）. Since water can float and be driven by the wind, plastics can cause great harm to creatures hundreds of feet from where they were originally dumped. Such waste includes bags, bottles, cups, straws （吸管）, cup lids （蓋子）, utensils （器具）, fishing line, and other floats （漂浮物）.
19.空氣汙染 Ⅰ
段落大意：空氣汙染關係到世界上每一個人，引起了人們廣泛的關注。要了解並防止空氣汙染，了解大氣的構成很重要。本段講述了大氣層的各組成部分。
Air pollution is a major problem affecting the entire world. In the United States some progress has been made in reducing air pollution through the Clean Air Acts passed by the Congress. Still there is a lot to be done. To prevent air pollution it is important to understand how the air is being polluted, how it impacts on the ecosystem and what we can do about it. Earth is surrounded by layers of gases known as atmosphere. The layer closest to the earth is called the troposphere （對流層）. It extends up to ten miles above the surface of the earth. Over the troposphere is the stratosphere （同溫層） which extends from ten to forty miles above the earth. Ozone is a part of the stratosphere that blocks the sun’s harmful ultraviolet rays （紫外線） from reaching the earth. Over the stratosphere is the ionosphere （電離層） which extends up to 400.miles. In the ionosphere, the gases are broken into individual electrically charged particles（粒子）called ions （離子）.