點擊查看：2018年大學英語四級考試美文匯總

　　考試吧英語四六級考試網為大家整理了英語四級美文，希望可以為大家帶來幫助，一起來欣賞吧。

　　1

　　Hotter or Colder ?

　　2

　　It was once thought that air pollution

　　3

　　affected only the area immediately around large cities

　　4

　　with factories and/or heavy automobile traffic.

　　5

　　Today, we know that although these are the areas

　　6

　　with the worst air pollution,

　　7

　　the problem is literally worldwide.

　　8

　　On several occasions over the past decade,

　　9

　　a heavy cloud of air pollution

　　10

　　has covered the entire eastern half of the United States

　　11

　　and led to health warnings even in rural areas

　　12

　　away from any major concentration of manufacturing

　　13

　　and automobile traffic.

　　14

　　In fact, the climate of the entire earth

　　15

　　may be affected by air pollution.

　　16

　　Some scientists feel

　　17

　　that the increasing concentration of carbon dioxide in the air

　　18

　　resulting from the burning of fossil fuels

　　19

　　(coal and oil)

　　20

　　is creating a “greenhouse effect” —

　　21

　　holding in heat reflected from the earth

　　22

　　and raising the world’s average temperature.

　　23

　　If this view is correct

　　24

　　and the world’s temperature is raised only a few degrees,

　　25

　　much of the polar ice cap will melt

　　26

　　and cities such as New York, Boston, Miami,

　　27

　　and New Orleans will be under water.

　　28

　　Another view, less widely held,

　　29

　　is that increasing particulate matter in the atmosphere

　　30

　　is blocking sunlight and lowering the earth’s temperature —

　　31

　　a result that would be equally disastrous.

　　32

　　A drop of just a few degrees could create something close to new ice age

　　33

　　and would make agriculture difficult

　　34

　　or impossible in many of our top farming areas.

　　35

　　At present we do not know for sure

　　36

　　that either of these conditions will happen

　　37

　　(though one recent government report

　　38

　　prepared by experts in the field concluded

　　39

　　that the greenhouse effect is very likely).

　　40

　　Perhaps, if we are very lucky,

　　41

　　the two tendencies will offset each other

　　42

　　and the world’s temperature will stay about the same

　　43

　　as it is now.

掃描/長按二維碼可幫助通過46級考試

獲取四六級考試資訊

獲取46級成績查詢時間

獲取精選四六級模擬題

獲取四六級考試技巧

四六級萬題庫 | 微信搜索"萬題庫英語四六級考試"

　　編輯推薦：

　　2018年英語四級作文 | 2018年英語四級詞匯

　　2018年英語四級聽力 | 2018年英語四級翻譯

　　歷年大學英語四級考試真題及答案|估分|下載

　　歷年大學英語四級考試真題聽力(含MP3)匯總

　　歷年大學英語四級考試萬題庫 智能做題首選！