Question 19 is based on the passage you have just heard.

Passage Two

    We know we have to pay for what we get. If we buy food, we have to pay for it. If a doctor treats us, we know there will be a bill to pay. These are private bills. But there are also public bills to be paid. They are paid by the government. In turn we get the needed services. （19）We pay for these services through taxes. What would happen if everyone stopped paying taxes? The water supply would stop; the streets might not be cleaned; schools would be closed. We would not want to live in such a city. （20）The chief duty of every government is to protect persons and property. More than three-fourths of government expenses are used for this purpose. The next largest amount of public money goes to teach and train our citizens. Billions of dollars each year are spent on schools and libraries. Also, a large amount of public funds is spent on roads. Most of the needed funds are raised by taxes. The law orders us to pay taxes. We have no choice in the matter. （21）Years ago the government made money by selling public lands. But most of the best public lands have now been sold. There are still some public lands that contain oil, coal and other natural resources. They could be sold, but we want to save them for future years. So, we all must pay our share for the services that make our lives comfortable.

19. What does the speaker mainly talk about?

解析：A。该题目为主旨题。问题是：本文主要讨论什么？主旨题出题位置在首段末尾处。根据选项得出关键词分别为：征税原因、各种的服务、各种负担、金钱作用。第一段首句“We know we have to pay for what we get”指出我们想获得什么都要付钱。尾句“We pay for these services through taxes”指出我们为服务付税。选项A）The reasons for imposing taxes，与原文信息相一致。或者在判断为主旨题时，先放置不做，等听完全文再做出选择，文章后续则讲述了税收的原因。因此，此题目正确答案为A。