INTRODUCTION Human population in the past 48 years has more than doubled its seize, from 2.5 billion in 1950 to 5.9 billion in 1998 . A few month ago the Secrtary of the United Nation declared a baby as the No. 6 billion citezen of the earth. As you may have noticed, human population has reached a size that threatened our environment and the sustainability of the earth. Is the earth bounded to face this number of human? In fact, in the …
showed first 75 words of 1464 total

showed last 75 words of 1464 total
…