单选题
A very important world problem is the increasing number of people who actually inhabit this planet. The limited amount of land and land resources will soon be unable to support the huge population if it continues to grow at its present rate.
So why is this huge increase in population taking place? It is really due to the spread of the knowledge and practice of what is becoming known as "Death Control". You have no doubt heard of the term "Birth Control". "Death Control" is something rather different. It recognizes the work of the doctors and scientists who now keep alive people who, not very long ago, would have died of a variety of then incurable diseases. Through a wide variety of technological innovations that include farming methods and the control of deadly diseases, we have found ways to reduce the rate at which we die. However, this success is the very cause of the greatest threat to mankind.
If we examine the amount of land available for this ever-increasing population, we begin to see the problem. If everyone on the planet had an equal share of land, we would each have about 50,000 square meters. This figure seems to be quite encouraging until we examine the amount of usable land we actually have. More than three-fifths of the world's land cannot produce food.
Obviously, with so little land to support us, we should be taking great care not to reduce it further. But we are not! Instead, we are consuming its "capital" its nonrenewable fossil fuels and other mineral deposits that took millions of years to form but which are now being destroyed in decades. We are also doing the same with other vital resources not usually thought of as being nonrenewable such as fertile soils, groundwater and the millions of other species that share the earth with us.
It is a very common belief that the problems of the population explosion are caused mainly by poor people living in poor countries who do not know enough to limit their reproduction. This is not true. The actual number of people in an area is not as important as the effect they have on nature. Developing countries do have an effect on their environment, but it is the populations of richer countries that have a far greater impact on the earth as a whole.

单选题 According to the article, what contributes to the population increase?

单选题 The word "incurable" in Paragraph 2 means______.

单选题 There isn't enough land to support human being because______.

单选题 In Paragraph 4 the writer implies that fertile soils are______.

单选题 What does "to limit their reproduction" in the last paragraph mean?