A.than B.which C.contribute A.These nutrients can【T1】______to the breeding of the organisms B.more【T2】______2,600 square k

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问题 A.than    B.which    C.contribute
A.These nutrients can【T1】______to the breeding of the organisms
B.more【T2】______2,600 square kilometers
C.【T3】______carry poisonous substances
    The term "red tide" applies to the discoloration of water that sometimes occurs in certain areas of the ocean or sea.Although the color is often red, it may also be shades of brown or yellow.The World Book Encyclopedia reports that "the discolored areas may range from less than a few square yards to【T4】______."
    What causes such discoloration? Red tides are generally caused by several species of single-celled organisms.These tiny organisms have hair-like projections which they use to propel themselves in water.There are about 2,000 varieties of these organisms, 30 of【T5】______.These minute organisms usually stay in warm waters with high content of salt.
    A red tide occurs when there is a sudden and rapid bloom of these organisms.The concentration of these organisms may swell to 50,000,000 per quart of water! Although scientists do not fully understand why this happens, it is known that these organisms accumulate when certain conditions simultaneously affect the water.These include abnormal weather, optimum temperatures, an oversupply of nutrients in the water, a generous amount of sunlight, and favorable water currents.When a heavy rainfall occurs, minerals and other nutrients are sometimes washed from the land into coastal water.【T6】______.The result? Red tides!
【T6】

选项

答案A

解析 空格前一句的意思为:这些环境包括反常的天气,适宜的湿度,海水中营养物的过度供应,充足的阳光以及起促进作用的水流。当出现暴雨时,矿物质和其他营养物有时被从陆地冲向沿海水域。空格后一句的意思为:结果是什么呢?所以,A项“这些营养物可能促进这些微生物的生长”符合题意。所以,答案是A。
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