第1题

　　Which of the following is NOT a type of phytoplankton?

　　A Green algae. B Diatoms. C Blue-green algae. D Amoeba.

　　【正确答案】：D

　　【答案解析】 [分析] 是非题型。 见文章第二段第一句：Marine phytoplankton (Greek for "plant wanderers")are microscopic single-celled plants that include diatoms, dinoflagellates, coccolithophorids, green algae, and blue-green algae, among others.说明海洋浮游生物包括：A.Green algae 绿藻;B.Diatoms 硅 藻属;C.Blue-green algae 蓝绿藻;等等。选项 D.“Amoeba 阿米巴虫”不包 括在内，所以是答案。

　　第2 题

　　The growth of phytoplankton is often limited by the availability of ______.

　　A oxygen B hydrogen C nitrogen D carbon dioxide

　　【正确答案】：C

　　【答案解析】[分析] 细节题型。 见文章第二段第二句：The growth of these organisms, which photosynthesize light, depends on a delicate balance of nutrient enrichment via vertical mixing, which is often limited by the availability of nitrogen and light.所以选项 C 正确。

　　第3题

　　The main idea of this passage is that ______.

　　A light causes sea color B sea coloration is varied because of a combination of length of light waves and microscopic plant life and silt C microscopic plant life causes sea color D water composition causes sea color

　　【正确答案】：B

　　【答案解析】 [分析] 主旨题型。 阅读全文得知，海水颜色的变化是由许多因素决定的;包括选项 A、C、D， 而选项B 是它们的综合，所以是答案。

　　第4题

　　The United States government publishes guidelines for appropriate nutrient intakes. These are known as the Recommended Dietary Allowances (RDAs) and are updated regularly based on new research in nutrition. RDAs are suggested amounts of calories, protein, and some minerals and vitamins for an adequate diet. For other dietary substances, specific goals must await further research. However, for the U.S. population as a whole, increasing starch and fiber in one's diet and reducing calories (primarily from fats. sugar, and alcohol) is sensible. These suggestions are especially appropriate for people who have other factors for chronic diseases due to family history of obesity, premature heart disease, diabetes, high blood pressure, and high blood cholesterol, or for those who use tobacco. Snacks can furnish about one-fourth of the calorie requirements among teenagers. Those snacks should also provide much of the day's allowances for protein, minerals, and vitamins. Sandwiches, fruit, and milk make good snacks for active teenagers. Food from the food pyramid may be part of any meal. A grilled cheese sandwich or a bowl of whole-grain cereal is just as nutritious in the morning as it is at noon. In addition, a good breakfast consists of any foods that supply about one-fourth of the necessary nutrients for the day. The passage directly states that most of the U.S. population should increase their intake of ______.

　　A protein B fats C starch and fiber D sandwiches

　　【正确答案】：C

　　【答案解析】 [分析] 细节题型。 见文章第一段倒数第二句：However，for the U.S. population as a whole， increasing starch and fiber in one's diet and reducing calories (primarily from fats, sugar, and alcohol) is sensible.选项 C 正确。

　　第5 题

　　A good breakfast should supply about what percentage of the necessary nutrients for the day?

　　A One-half. B One-third. C One-fourth. D Less than one-fourth.

　　【正确答案】：C

　　【答案解析】 [分析] 细节题型。见文章最后一句：„good breakfast consists of any foods that supply about one-fourth of the necessary nutrients for the day. 选项 C 正确。

　　第6题 The passage implies which of the following?

　　A The time of day when food is consumed affects its nutritive value. B Different foods can be combined to increase total nutrition value. C It can be detrimental to your health to eat breakfast foods later in the day. D When food is eaten has no bearing on its nutritive effects.

　　【正确答案】：B

　　【答案解析】 [分析] 推断题型。本文第一段第一和第三句介绍：美国政府公布了饮食中合理慑入营养的指导，且建议要有合理的热量、蛋白质、矿物质和维生素的摄入量;文章第二段第四句 Food from the food pyramid may be part of any meal.说明每顿饭都是由食 物金字塔里的食物构成的。由此推出摄取不同的食物可增加营养价值，选项B正确。

　　第7 题 Why are RDAs regularly updated?

　　A New discoveries in the science of nutrition are constantly being made. B Americans' diets are constantly changing.

　　C As people age, their nutritional needs change. D Very little is currently known about nutrition.

　　【正确答案】：A

　　【答案解析】 [分析] 细节题型。从文章第二句(These are known as the Recommended Dietary Allowances(RDAs)and are updated regularly based on new research in nutrition. )得知 RDAs 会根据营养学卜的新发现经常更新推荐的日摄食量。所以“推荐的日摄食量经常更新的原因是营养学上经常有新的发现”，选项A正确。