There was a time when a trip to the supermarket in the United States often ended with a seemingly simple question from the cashier："Paper or plastic？"Well，which type of bag would you choose?

　　While all types of bags have some influence on the environment，it has long been supposed that paper bags are kinder. They are made from a renewable source，break down easily，burn without giving off thick smoke and can be recycled. However，the producing process behind paper bags uses more energy than that of plastic ones. How can this be true?

　　Studies show that paper bag production requires four times as much energy as plastic bag production. And the amount of water used to make the miss twenty times higher. Besides，the influence on forests is very serious. It takes about fourteen million trees to produce ten billion paper bags，which happens to be the number of bags used in the United States yearly. In terms of recycling，the idea that paper bags are more environment­friendly than plastic ones can be quickly discarded. Research shows it requires about 98% less energy to recycle plastic than it does paper.

　　Even though paper bags might be more harmful than plastic ones，plastic still seems to be considered by governments as the more harmful of the two. In Ireland，for example，a tax has been introduced to discourage the use of plastic bags. People have to pay 22 cents for every plastic bag，and as a result，their use has dropped quickly.

　　There's no doubt that it makes more sense to reuse these bags. However，we don't seem to be doing that at present. That may be because they fall apart quickly. If so，cloth bags are a better choice，but still，their production also has a bad influence on the environment. So what to do？How should we answer the question of "Paper or plastic？"It seems that we first need to ask ourselves one more general question："What can I do to help the environment？"

语篇解读　文章列举了一些数据来说明纸袋和塑料袋哪种更环保。不管怎样，如何保护环境是我们所有人都需要关注的。

5．The questions in Paragraph 1 are used to_____________.

A．express the author's doubts

B．tell readers how to save money

C．introduce points for discussion

D．show the kindness of the cashier

答案　C

解析　推理判断题。文章第一段说到"去超市购物，售货员最后问我们用纸袋还是塑料袋"的问题，引出下文关于环保的讨论，可知第一段的问题被用来引出下文要介绍的话题。故