A very important world problem, if not the most serious of all the great world problems which affect us at the moment, 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.
In an early survey conducted in 1888, a billion and a half people inhabited the earth. Now, the population exceeds five billion and is growing fast—by the staggering figure of 90 million in 1988 alone. This means that the world must accommodate a new population roughly equal to that of the United States and Canada every three years! Even though the rate of growth has begun to slow down, most experts believe the population size will still pass eight billion during the next 50 years.
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 sanitation, as well as the control of these deadly diseases, we have found ways to reduce the rate at which we die—creating a population explosion. We used to think that reaching seventy years old was a remarkable achievement, but now eighty or even ninety is becoming recognized as the normal life-span for humans. In a sense, this represents a tremendous achievement for our species. Biologically this is the very definition of success and we have undoubtedly become the dominant animal on the planet. However, this success is the very cause of the greatest threat to mankind.
Man is constantly destroying the very resources which keep him alive. He is destroying the balance of nature which regulates climate and the atmosphere, produces and maintains healthy soils, provides food from the seas, etc. In short, by only considering our needs of today we are ensuring there will be no tomorrow.
An understanding of man’s effect on the balance of nature is crucial to be able to find the appropriate remedial action. 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.
The birth of a baby in, for example, Japan, imposes more than a hundred times the amount of stress on the world’s resources as a baby in India. Most people in India do not grow up to own cars or air-conditioners—nor do they eat the huge amount of meat and fish that the Japanese child does. Their life-styles do not require vast quantities of minerals and energy. Also, they are aware of the requirements of the land around them and try to put something back into nature to replace what they take out.
For example, tropical forests are known to be essential to the balance of nature yet we are destroying them at an incredible rate. They are being cleared not to benefit the natives of that country, but to satisfy the needs of richer countries. Central American forests are being destroyed for pastureland to make pet food in the United States cheaper; in Papua New Guinea, forests are destroyed to supply cheaper cardboard packaging for Japanese electronic products; in Burma and Thailand, forests have been destroyed to produce more attractive furniture in Singapore and Japan. Therefore, a rich person living thousands of miles away may cause more tropical forest destruction than a poor person living in the forest itself.
In short then, it is everybody’s duty to safeguard the future of mankind-not only through population control, but by being more aware of the effect his actions have on nature. Nature is both fragile and powerful. It is very easily destroyed; on the other hand, it can so easily destroy its most aggressive enemy—man.
In paragraph 3, which of the following is NOT given as a reason for a reduction in death rates（）
A. New inventions
B. Better hygiene
C. Improved food production
D. Better control of fatal diseases
C(金刚石，s)△H>O，所以金刚石比石墨稳定
和
的质子数相同，互为同位素