[单项选择]

Ozone is a form of oxygen. It is found in the air we breathe and in the upper atmosphere. Near the Earth, ozone in the air is a danger to life because it is a pollutant. But between ten and fifty kilometers up in the atmosphere, ozone protects life on the Earth. Ozone forms in the atmosphere through the action of radiation from the sun. Ozone blocks harmful radiation from reaching the Earth. Scientists say a decrease in ozone and an increase in the harmful radiation will cause many more cases of skin cancer. And it will harm crops, animals and fish.
Ozone problems first became known in 1985. British scientists reported that ozone levels in the Antarctic atmosphere near the South Pole fell sharply each year in October and November. 1987 was the first year that a huge hole developed in the ozone layer above the Antarctic.
A recent study of the atmosphere over the Arctic area near the North Pole showed extreme thinning of the ozone. Officials from the America
A. Between ten and fifty kilometers up in the atmosphere.
B. In the far sky.
C. Near the sun.
D. Far from the sun.

[单项选择]Ozone is a form of oxygen. It is found in the air we breathe and in the upper atmosphere. Near the Earth, ozone in the air is a danger to life because it is a pollutant. But between ten and fifty kilometers up in the atmosphere, ozone protects life on the Earth. Ozone forms in the atmosphere through the action of radiation from the sun. Ozone blocks harmful radiation from reaching the Earth. Scientists say a decrease in ozone and an increase in the harmful radiation will cause many more cases of skin cancer. And it will harm crops, animals and fish.
Ozone problems first became known in 1985. British scientists reported that ozone levels in the Antarctic atmosphere near the South Pole fell sharply each year in October and November. 1987 was the first year that a huge hole developed in the ozone layer above the Antarctic.
A recent study of the atmosphere over the Arctic area near the North Pole showed extreme thinning of the ozone. Officials from the American space agency s
A. harmful
B. a form of oxygen
C. rare
D. oxygen

[单项选择]Acid rain, which is a form of air pollution, currently becomes a subject of great debate because of widespread environmental damage for which it has been blamed. It forms when oxides of sulfur (硫) and nitrogen (氮) combine with atmospheric moisture to yield sulfuric and nitric acids, which may then be carried long distances from their source before they drop in the form of rain. The pollution may also take the form of snow or fog or fall down in dry forms. In fact, although the term "acid rain" has been in use for more than a century — it is derived from atmospheric studies that were made in the region of Manchester, England — the more accurate scientific term would be "acid deposition". The dry form of such deposition is just as damaging to the environment as the liquid form.
The problem of acid rain originated with the Industrial Revolution, and it has been growing ever since. The severity of its effects has long been recognized in local settings, as exemplified by the spells of
A. acid rain has caused air pollution
B. acid rain has caused widespread environmental damage
C. acid rain has become a much-studied subject
D. acid rain travels in all directions before it rains down

[简答题]

Acid rain, is a form of air pollution, currently a subject of great controversy because of widespread environmental damage for which it has been blamed. It forms when oxides of sulfur and nitrogen combine with atmospheric moisture to yield sulfuric and nitric acids, which may then be carded long distances from their source before they are deposited by rain. The pollution many also take the form of snow or fog or be precipitated in dry forms. In fact, although the term "acid rain" has been in use for more than a century — it is derived from atmospheric studies that were made in the region of Manchester, England — the more accurate scientific term would be "acid deposition." The dry form of such precipitation is just as damaging as the liquid form, especially to trees and structures. Furthermore, some of the pollutants also associated with acid rain are not themselves acidic.
The problem of acid rain may be said to have originated with the Indust

[简答题]It found that increases in air pollution tended to ______.

[单项选择]
Scientists say they have discovered hints of alien life on the Saturn’s moon. The discovery of a sort of life was announced after researchers at the US space agency, NASA, analyzed data from spacecraft Cassini, which pointed to the existence of methane-based form of life on Saturn’s biggest moon.
Scientists have reportedly discovered clues showing primitive alien beings are "breathing" in Titan’s dense atmosphere filled with hydrogen.
They argue that hydrogen gets absorbed before hitting Titan’s planet-like surface covered with methane lakes and rivers. This, they say, points to the existence of some "bugs" consuming the hydrogen at the surface of the moon less than half the size of the Earth.
"We suggested hydrogen consumption because it’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth," says NASA scientist Chris McKay. "If these signs
A. Gas-based life.
B. Methane-based life.
C. Water-based life.
D. Liquid-water-based microorganisms.