In wet areas of the world, the gain from trees absorbing carbon dioxide above
ground seems to be outweighed(超过) by the loss of carbon from the soil below ground. Countries that plan to combatglobal warming by planting trees may have to think again.
Solutions to environmental problems are often more complex than they first appear, and understanding the Earth’s climate is a very great challenge. 12．People usually hold the opinion that . A．huge dust storms can destroy carbon dioxide
B．huge dust storms can destroy the oceans on the earth C．huge dust storms can’t do anything beneficial for man D．planting trees is the only way to control huge dust storms 13．Andy Ridgwell, the environmental scientist, believes that . A．dust plays a more important part than trees B．trees shouldn’t have been planted in dry places C．carbon dioxide is harmful to everything on the earth D．environmental problems are more complex than expected 14．Robert Jackson’s experiment proves that . A．grassland areas should be covered by forests B．trees hold more carbon than grasses C．carbon can turn grass into dust D．less carbon can make trees grow faster
15．The underlined word “combat” in the last paragraph means . A．learn about B．fight
against C．live with D．give up 第二节（共五小题，每小题2分，共10分）
根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。(共5小题；每小题1分，满分5分)
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