The hole in the earth's protective ozone layer（臭氧层）won't repair itself until about two decades later than had been expected, scientists announced.
The ozone layer blocks more than 90 percent of the sun's ultraviolet radiation（紫外线辐射）, helping to make life on Earth possible. For many dacades, ozone was depleted（削减） by chlorine and bromine gas in the air. A hole in the ozone layer formed over the Southern Hemisphere.
Computer models had forecast that the hole would fill back in by 2050. An improved computer model forecasts the recovery won't occur until 2068. The model, fed with fresh data from statellites and airplanes, was supported by the fact that it accurately reproduced ozone levels in the Antarctic stratosphere（平流层）over the past 27 years.
The ozone hole is actually more of a broad region with less ozone than ought to occur naturally. It is not limited to Antarctica, as is often believed.
Over areas that are farther from the poles like Africa or the US, the levels of ozone are only three to six percent below natural levels. Over Antarctica, ozone levels are 70 percent lower in the spring. This new method allows us to more accurately estimate（估计）ozone-depleting gases over Antarctica, and how they will decrease over time, reducing the ozone hole area.
Paul Newman, a scientist,said that the ozone hole has not started to become smaller as quickly as expected. They figure it will not become much smaller until 2018, after which time the recovery should proceed more quickly. And the hole will not be filled in again until 2065.
小题1:According to the passage, the ozone layer _______
A．absorbs as much as sunlight as possible
B．protects man against ultraviolet radiation
C．controls the changes in temperature
D．prevents the production of carbon dioxide小题2:The improved computer model is believable because _________
A．it was once proved by facts
B．it has been studied for 27 years
C．it was created by many scientists
D．it is related to satellites and airplanes小题3:The underlined word “they” in the fifth paragraph refers to ________
A．the levels of ozone
B．ozone-depleting gases
C．the ozone holes
D．the areas far from the poles
