Populationtends to grow at an exponential(指数的)rate. This means that they progressivelydouble. As an example of this type of growth rate take one penny anddouble every day for one month. After the first week, you would have only 64 cent, but after the fourth week you would haveover a million dollars.
This helps explain why the population has e on“all ofa sudden” took fromhe beginning ofhuman1ife to the year 1830 for the population of the earth to reach one billion. Thatrepents(缓慢进行) a time span ofatleasttwo millionyears. Then it took from 1830to 1930forworldpopulationto reach 2 billion. The nextbillionwasadded by1960 only thirty years and in 1975 world population reached 4 billion which isanother billion people in only fifteen years.
World population isincreasing at a rate of 9, 000perhour, 220,000 perday and 80million per year.
This is not only due to higher birth rate, but to lower death rate as well. The number ofbirths has not declined at the same rate as the number of deaths.
Some countries such as Columbia, Thailand, Morocco, Costa Rica and the Philippines aredoublingtheirpopulation abouteverytwenty-oneyears with a growth rate of 3.3 percent a year or more. The United States is doubling its population about very eighty-seven years, with a rate of 0.8 percent per year. Every time a population doubles, the country involved needs twice as much of everything, including hospitals, schools, resources,food and medicines to care for its people. It is easy to see that this is very difficult to achieve for the more rapidly growing countries.
1. This passage chiefly discusses A. thegrowth ofworld population.
B. one type of the exponential rate. C. the population problem of more rapidly growing countries. D. the possible ways ofdealing with the rapid populationgrowth.
2. According to the passage what helps to explain why the population problem has e on “all