from the graph we can see the health gains in developing cotmtries. in l960, the average life span or life expectancy was only 40 years old. in 1990, after thirty years, the life expectancy rose to 60. at the same time, with the life expectancy going up, the infant mortality is coming down. in 1960 the infant mortality was 200 deaths per 1000 births. that is, about 200 infants died at birth among 1000 babies born. in 1990, the infant mortality declined to 100 deaths per 1000 births.

　　what are the reasons for this situation? i think it lies in three respects. first, economy is developing as time progresses. people am better off than before. second, education plays an important role. people are better educated and more civilized. they are more aware that good health ensures success in life and work, third, the government pays more attention to the protection of the environment.

　　more measures are being taken to deal with the problem of pollution. that is why life expectancy is on the rise and infant mortality on the decline.