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职称英语卫生类考试考前每日一练 阅读下面这篇短文，短文后有2项测试任务：第23～26题要求从所给的6个选项中为第2～5段每段选择1个正确的小标题;第27~30题要求从所给的6个选项中选择4个正确选项，分别完成每个句子。请将答案涂在答题卡相应的位置上。 The molecules of carbon dioxide in the Earths atmosphere affect the heat balance of the Earth by acting as a one-way screen. Although these molecules allow radiation at visi-ble wavelengths, where most of the energy of sunlight is concentrated, to pass through,they absorb some of the longer-wavelength infrared emissions radiated from the Earth s surface, radiation that would otherwise be transmitted back into space. For the Earth to maintain a constant average temperature, such emissions from the planet must balance in- coming solar radiation. If there were no carbon dioxide in the atmosphere, heat would es-cape from the Earth much more easily. The surface temperature would be so much lower that the oceans might be a solid mass of ice. Today, however, the potential problem is too much carbon dioxide. The burning of fossil fuels and the clearing of the forests have increased atmospheric carbon dioxide by a- bout 15 percent in the 1st hundred years, and we continue to add carbon dioxide to the at- mosphere. Could the increase in carbon dioxide cause a global rise in average temperature and could such a rise have serious consequences for human society? Mathematical models, that allow us to calculate the rise in temperature as a function of the increase indicate that the answer is probably yes. | 
