Directions: In this part, there is a passage with ten blanks. For each blank there are four choices marked A,B,C and D. Choose the best answer for each blank and mark your answer on the ANSWER SHEET.

　　A . These nutrients can ( 1 )_______to the breeding of the organisms

　　B . more ( 2 )______ 2 , 600 square kilometers

　　C . ( 3)________ 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 ( 4 )_______. "

　　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 (5)_______. These minuteorganismsusually 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, 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. (6) _ . The result? Red tides!

　　答案解析：

　　1. 【答案】contribute

　　【解析】 本題主要考查固定搭配。contribute to 為固定搭配，是“有助于，捐獻(xiàn)”的意思，符合題意。所以，答案是contribute 。

　　2. 【答案】than

　　【解析】 本題主要考查固定搭配。more than 為固定用法，后面接數(shù)詞，是“多于”的意思，符合題意。所以，答案是than 。

　　3. 【答案】which

　　【 解析】 本題考查定語(yǔ)從句的連接詞。分析句子結(jié)構(gòu)可知，此處為非限制性定語(yǔ)從句，所以應(yīng)填關(guān)系代詞which 。所以，答案是which 。

　　4. 【答案】B

　　【解析】空格所在句的意思為：《 世界書籍百科全書》 介紹說，“變色的區(qū)域可能在不少于幾平方碼到2 600 平方千米之間。”所以，B 項(xiàng)符合題意。所以，答案是B。

　　5. 【答案】C

　　【解析】空格所在句的意思為：大約有2 000 種這樣的生物，其中的30 種攜帶有毒物質(zhì)。這些微生物通常生活于含鹽量高的溫帶水域。所以，C 項(xiàng)“攜帶有毒物質(zhì)”符合題意。所以，答案是C 。

　　6. 【答案】 A

　　【 解析】 空格前一句的意思為：這些環(huán)境包括反常的天氣，適宜的濕度，海水中營(yíng)養(yǎng)物的過度供應(yīng)，充足的陽(yáng)光以及起促進(jìn)作用的水流。當(dāng)出現(xiàn)暴雨時(shí)，礦物質(zhì)和其他營(yíng)養(yǎng)物有時(shí)被從陸地沖向沿海水域�？崭窈笠痪涞囊馑紴椋航Y(jié)果是什么呢?所以，A 項(xiàng)“這些營(yíng)養(yǎng)物可能促進(jìn)這些微生物的生長(zhǎng)”符合題意。所以，答案是A 。