【答案解析】{{B}} Make Our Cities Greener{{/B}} With rapid growth of modem cities, urban vegetation has been greatly reduced. Stifled by the polluted air, many trees and grasses die. Besides, more buildings are being built to house the rapidly increasing population, and they contend with plants for land. As a result, cities are becoming less greener than before. However, plants are essential to the living of people in cities. First, they help to purify the air. Next, they add to the beauty of the surroundings we live in. Finally, tall and big trees protect us from the scorching heat of the sun. Therefore, effective measures must be taken to ensure a sufficient amount of vegetation in cities. Government should enact strict laws to prevent people from cutting down trees. As dwellers in the cities, we should plant more trees and grow more grasses. Then cities will become greener.