人与社会：耕作的土地 星期五 阅读理解＋七选五 分值：22.5分 Ⅰ.阅读理解(每小题2.5分，共10分) If the grass looks greener after the skies have cleared，your eyes aren’t cheating you.After it rains，there’s typically more water available in the soil to plants.When plants take in that water，they are also taking in nitrogen(氮) from the organic matter that’s in the soil. As plants grow，their small roots die and new roots grow.When that happens，soil microbes(微生物) contribute to the dead roots’ being destroyed gradually by natural processes.The roots have many chemical substances that consist mostly of carbon but also some nitrogen.Soil microbes use carbon and some of the nitrogen to cause the dead roots to rot.As this happens，an amount of the nitrogen is sent back into the soil as a sort of waste product. As rain goes into the soil，it makes the microbes active and release more nitrogen.The grass benefits from the freshly fallen rain because an amount of water allows the roots to take in this “new” nitrogen as well as the nitrogen that the microbes previously released. Something else happens to nitrogen when it rains.The atmosphere is made up of 78 percent nitrogen gas.When it rains，the rain brings some of the nitrogen down onto grass.However，only a small amount of the nitrogen that falls directly on grass during rain events is directly absorbed into the leaves—and this might surprise you. Even though rain helps increase the nitrogen that is available to grass in several ways，you can’t count on nitrogen from rain to meet all of the fertilizer needs of your grass or your vegetable garden.Commercial fertilizers or organic soil nutrients are still needed for a balanced fertilizer program.While nitrogen is necessary for good plant growth，be sure to follow package directions.Too much of a good thing can be harmful not only to plants but to nearby rivers. 1．What does the underlined word “this” in paragraph 2 refer to A．The birth of new roots. B．The death of old roots. C．The activation of microbes. D．The breakdown of dead roots. 2．What makes the grass look greener after rain A．The sun. B．The nitrogen. C．The fertilizer. D．The microbe. 3．What are people advised to do in the end A．Protect rivers from fertilizer. B．Guarantee the richness of the soil. C．Be cautious about using fertilizer. D．Realize rain’s importance to plants. 4．Which is the best title for the text A. Why Is Grass Greener After It Rains B．What Are Effects of Nitrogen on Grass C．How Much Fertilizer Does Grass Need D．When Should You Fertilize New Grass 读写积累 1．typically adv.典型地，有代表性地 2．previously adv.之前地，早先地 3．take in熟义：吸入，收留(本文为此义) 生义：理解；欺骗 4．contribute to 造成，促使 5．consist of由……构成 (无被动和进行) 6．be absorbed into 被吸收进去 7．count on依靠，依赖，指望 8．meet all needs满足所有需要 9．While nitrogen is necessary for good plant growth，be sure to follow package directions. 句式结构：while引导的让步状语从句 ... ...
