A、Population explosion. B、Extinction of rare species. C、Chronic hunger. D、Environmental deterioration. C浏览四个选项，根据选项中出现的populatio

Why should you consider taking a course in demography in college? You’ll be growing up in a generation where the baby boomers are going into retirement and dying. You will face problems in the aging of the population that have never been faced before. You will hear more and more about migration between countries and between rural areas and cities. You need to understand as a citizen and as a tax payer and as a voter what’s really behind the arguments.
    I want to tell you about the past, present and future of the human population. So let’s start with a few problems. [23] Right now, a billion people are chronically hungry. That means they wake up hungry, they are hungry all day, and they go to sleep hungry. A billion people are living in slums, not the same billion people, but there is some overlap. Living in slums means they don’t have infrastructure to take the garbage away, they don’t have secure water supplies to drink.
    Nearly a billion people are illiterate. Try to imagine your life being illiterate. You can’t read the labels on the bottles in the supermarket, if you can get to a supermarket. Two-thirds of those people who are illiterate are women and about 200 to 215 million women don’t have access to birth control they want, so that they can control their own fertility. This is not only a problem in developing countries. [24] About half of all pregnancies globally are unintended. So those are examples of population problems.
    Demography gives you the tools to understand and to address these problems. It’s not only the study of human population, but the populations of non-human species, including viruses like influenza, the bacteria in your gut, plants that you eat, animals that you enjoy or that provide you with meat. Demography also includes the study of non-living objects like light bulbs and taxi cabs, and buildings because these are also populations. It studies these populations, in the past, present and future, using quantitative data and mathematical models as tools of analysis.
    [25] I see demography as a central subject related to economics. It is the means to intervene more wisely, and more effectively in the real world, to improve the wellbeing, not only of yourself—important as that may be—but of people around you and of other species with whom we share the planet.
Questions 23 to 25 are based on the recording you have just heard.
23. What is one of the problems the speaker mentions in his talk?
24. What does the speaker say about pregnancies?
25. How does the speaker view the study of populations?