题目内容：

A vegetarian diet is often praised for its health benefits. Vegetarians usually have lower levels of heart disease, and studies have also shown that they have a lower risk of diabetes(糖尿病)than people who eat meat. However, most people don't realize that a vegetarian diet produces less pollution to the earth.

Researchers from the Union of Concerned Scientists in the US recently studied how people affect the environment. The study showed that eating meat is one of the main ways that humans can change the environment, second only to the use of motor vehicle.

Then, how can eating meat have a negative effect on the environment? For a start, all farm animals such as cows, pigs, and sheep give off methane gas(沼气)by breathing. One cow can produce up to 60 liters of methane each day. Methane gas is the second most common greenhouse gas after carbon dioxide. Many environmental experts now believe that it is more responsible for global warming than carbon dioxide. It is estimated that 25% of all methane released into the air comes from farm animals.

Another way that meat production affects the environment is through the use of water and land. 2,500 gallons of water are needed to produce one pound of beef while only 20 gallons of water are needed to produce one pound of wheat. One acre of farmland used for crop production can produce 40,000 pounds of potatoes, 30,000 pounds of carrots, or 50,000 pounds of tomatoes, however, one acre of farmland used for raising cows can produce just 250 pounds of beef.

Many people now see the benefits of a vegetarian diet, not just for health reasons, but also because it plays an important role in protecting the environment. However, some nutritionists advise against switching to a totally strict vegetarian, or vegan diet. They believe a vegan diet, which excludes(拒绝) all products from animal sources, such as cheese, eggs, and milk, can be short of many necessary vitamins and minerals our bodies need.

Today, many people know that it is important to take better care of their bodies, and to use the earth's resources more efficiently. As this understanding spreads, more people may realize that to help the environment and for the human race to survive, more of us will need to become vegetarian.

1.The underlined word "vegetarian" in the first paragraph most probably means "      ".

A. a person who eats healthy food

B. a person who eats meat and vegetables

C. a person who only eats meat, fish and seafood

D. a person who only eats vegetables，grains, and fruit

2.It's         for a vegetarian to have diabetes than a person who eats meat.

A. more possible    B. less possible

C. highly possible    D. impossible

3.Which of the statement is TRUE according to the article?

A. Doctors suggest switching to totally vegetarian diets.

B. It takes more water and land to produce a kilo of crops.

C. Farm animals give off methane gas and pollute the environment.

D. Carbon dioxide is more responsible for global warming than methane gas.

4.The underlined word "it" in Paragraph 5 refers to "      ".

A. a vegetarian diet    B. animal source

C. necessary vitamin    D. health reason

5.The main idea of the article is that         .

A. our diet is destroying the surroundings

B. raising farm animals affects the environment

C. a vegetarian diet helps to protect the environment

D. more and more people are becoming strict vegetarians