Choose the most appropriate words or phrases to co...
Choose the most appropriate words or phrases to complete the following passage. Every year there are changes 1)_________ (on/in) different parts of the world. Some of these changes are 2)___________ (due to/result in) natural causes. 3)__________ (Because/However), some climate changes are caused by air pollution and these changes may increase. If the pollution 4) __________ (effects/affects) the level of carbon dioxide(二氧化碳) in the atmosphere, the results 5) _____________ (are alike to/are likely to) be serious. Carbon dioxide constitutes only a small part of the 6) ___________ (atmosphere/climate), but it has an important function in 7) ____________ (maintaining/insisting) the balance between radiation 8) _____________ (to/from) the sun entering the atmosphere and radiation leaving the Earth. Some of the radiation is absorbed by the Earth and some is radiated back into the atmosphere. The carbon dioxide in the atmosphere prevents some of the radiation 9) _________ of/from) leaving the atmosphere. Thus the heat 10) _________ (remains/keeps) in the atmosphere and carbon dioxide helps to prevent the temperature of the Earth from falling. If the 11) __________ (rate/proportion) of carbon dioxide in the atmosphere is increased as a result of air pollution, the temperature of the atmosphere may 12) _________ (rise/fall). This might eventually cause the ice in the North and South Poles to melt. If this 13) __________ (happening/happened), the sea level could rise and parts of the Earth 14) ___________ (would/will) be flooded. The likelihood of this happening is unknown, but the possibility 15) ________ (exists/existed).