A vegetarian diet is often praised for its health benefits. Studies have shown that vegetarians usually have lower levels of heart disease and a lower risk of diabetes than people who eat meat. What most people are less aware of, however, are the effects that a vegetarian diet can have on the environment.

Researchers from the Union of Concerned Scientists in the US recently studied how consumer behavior affects the environment. The study showed that meat consumption is one of the main ways that humans can damage 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 (沼气) gas by expelling (排出) wind from their bodies. 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 atmosphere 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, whereas 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.

Many people now see the benefits of switching to a vegetarian diet, not just for health reasons, but also because it plays a vital 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 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 it’s 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 vegetarians.

【1】The underlined word “it” in Para.3 refers to ___________.

A.methane gasB.carbon dioxide

C.expelling windD.greenhouse gas

【2】Many figures are used in Para.4 to show ___________.

A.growing tomatoes has the highest production

B.crop production is better than meat production

C.meat production consumes too much water and land

D.farm animals are the main producer of the methane gas

【3】What message does the passage want to convey?

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.

【答案】

【1】A

【2】C

【3】C

【解析】

本文是一篇说明文。文章介绍了素食不仅有益于健康，而且还会对环境产生积极的影响。

【1】词义猜测题。根据画线词前的“Methane gas is the second most common greenhouse gas after carbon dioxide.”可知，甲烷气体是仅次于二氧化碳的第二大温室气体，此处是甲烷气体和二氧化碳的对比，即：许多环境专家现在认为甲烷气体比二氧化碳更能导致全球变暖。由此可知，it指代的就是前面提到的甲烷气体，故A项正确。

【2】推理判断题。根据第四段中的“Another way that meat production affects the environment is through the use of water and land.”可知，肉类生产影响环境的另一种方式是利用水和土地，紧接着通过具体数据对肉类生产和蔬菜种植所需的土地和水进行对比——生产一磅牛肉需要2500加仑水，而生产一磅小麦需要20加仑水；一英亩的农田可以生产4万磅土豆、3万磅胡萝卜或5万磅西红柿。由此可知，这些数据就是为了证明肉类生产消耗了太多的水和土地，故C项正确。

【3】主旨大意题。通读全文，特别是根据第一段中的“What most people are less aware of, however, are the effects that a vegetarian diet can have on the environment.”可知，然而，大多数人不太清楚的是素食对环境的影响，因此文章主要讲的是素食有助于保护环境，故C项正确。

代词指代形式的词义猜测题难度较大，因为代词指代的都是上文出现的某个（些）名词或名词性短语，因此抓住画线词上文出现过的名词或名词性短语是关键，例如本篇第1题，根据画线词前的“Methane gas is the second most common greenhouse gas after carbon dioxide.”可知，甲烷气体是仅次于二氧化碳的第二大温室气体，此处是甲烷气体和二氧化碳在影响环境方面的对比，即：许多环境专家现在认为甲烷气体比二氧化碳更能导致全球变暖，由此可知it指代的就是前面提到的甲烷气体。