问题 选择题

在食物的营养成分中,糖类的主要作用是(  )

A.为生理活动提供能量

B.体内贮存的物质

C.构成细胞的基本物质

D.调节新陈代谢

答案

人体生活需要的六大类营养物质是:糖类、蛋白质、脂肪、维生素、水和无机盐.其中糖类、蛋白质、脂肪属于大分子有机物,贮存着能量,在人体内都能氧化分解,为人体的生命活动提供能量.其中糖类是最重要的供能物质,人体进行各项生命活动所消耗的能量主要来自于糖类的氧化分解,约占人体能量供应量的70%.脂肪也是重要的供能物质,但是人体内的大部分脂肪作为备用能源贮存在皮下等处,属于贮备能源物质.蛋白质也能为生命活动提供一部分能量,但蛋白质主要是构成组织细胞的基本物质,是人体生长发育、组织更新的重要原料,也是生命活动的调节等的物质基础.维生素属于有机物,但它既不能为人体提供能量,也不参与人体组织的构成,但它对人体的生命活动具有重要的调节作用.水和无机盐属于无机物.其中水既是人体重要的构成成分,也是人体各项生命活动进行载体.许多无机盐是人体重要的构成成分.

故选:A

阅读理解

阅读理解。

      Man is a land animal, but he is also closely tied to the sea. Throughout history the sea has served

the needs of man. The sea has provided man with food and a convenient way to travel to many parts

of the world. Today, nearly two-thirds of the world's population live within 80 kilometers of the sea

coast.

      In the modern technological world, the sea offers many resources to help mankind survive.

Resources on land are beginning to be used up. The sea, however, still can be hoped to supply many

of man's needs.

     The list of riches of the sea yet to be developed by man's technology is impressive. Oil and gas

explorations have been carried out for nearly 30 years. Valuable amounts of minerals exist on the

ocean floor ready to be mined.

     Fish farming promises to be a good way to produce large quantities of food. The culture of fish

and shellfish is an ancient skill practiced in the past mainly by Oriental people.

     Besides oil and gas, the sea may offer new sources of energy. Experts believe that the warm

temperature of the ocean can be used in a way similar to the steam in a steamship. Ocean currents

and waves offer possible use as a source of energy.

     Technology is enabling man to explore ever more deeply under the sea. The development of

strong, new materials has made this possible.

     The technology to harvest the sea continues to improve. Experts believe that by the year 2050

the problems that prevent us from exploiting fully the food, minerals, and energy sources of the sea

will be largely solved.

1. What is the beat title for the passage?

A. Needs of Man.              

B. Sea Harvest and Food

C. Sea and Sources of Energy    

D. Sea Exploring Technology.

2. It can be inferred from the passage that ______.

A. man hasn't completely made use of the riches of the sea

B. technology for exploring the sea has been solved

C. harvesting rice in the sea will be made possible

D. in the near future man can live on the ocean floor

3. Why does the author mention a steamship in paragraph 5?

A. To illustrate that man can make use of sources of energy from the sea.

B. To show that a steamship is better than other kinds of ships.

C. To argue that man should use steamships.

D. To indicate that it is warmer in the ocean than on land.

4. According to the author, technology is important because ______.

A. resources on land are running short in ten years

B. man can use it to explore the deeper sea

C. it is a lot of fun diving into the sea

D. ancient people used it to explore the sea

5. According to the author, when will the problems to explore the deeper sea largely be solved?

A. In the next generation.              

B. At the end of the 20th century.

C. In the near future.                  

D. By the middle of the 21st century.

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