The human population is about 7,000 million people and growing steadily.How many significant digit我想问的是把7000 million 写成科学计数法后，有机位有效数字！一般写成7.0x10^9 有几个有效数字？

statistical study of the human population how does the expansion of human population affect the animals?中文含义是什么？ study of human populationi want to know what are the causes that affect the increase and decrease the percentage of human population. the effects of such a change in weather on human population of the world would be frightening “The effects of such a change in weather on human population of the world woud be frightening” the professor wants to predit the problems and needs of human population and its incressing impact on natural resources like water and land. 4551 什么意思? 区分a population of/the population of 麻烦达人帮忙查下文章是否被SCI检索 Biologic characteristics of the side population of human small ce 求译：the human population of the world may be anything from twice tothe human population of the world may be anything from twice to three times the present total by 2070.最好帮忙说明下句子结构.主要是anything the professor wants to predit the problems and needs of human population and its incressing impact the professor wants to predict the problems and needs of human population and its increasing impact on natural resources like water and land.4551 想 the professor wants to predict the problems and needs of human population and its increasing impact on natural resources like water and land.4551 想知道的语言点：1—the professor wants to predict the problems and needs of human population THE HUMAN USE OF HUMAN BEINGS怎么样 The Human League的《Human》 歌词 the killers-《human》lyrics 这即是The human nature! the human stain 歌词 The Human Touch! the human race