This pattern is important to notice. Not only does it put the current problems of demographic growth into a historical perspective, but it suggests that the cause of rapid increase in population in recent years is not a sudden enthusiasm for more children, but an improvement in the conditions that traditionally have caused high mortality.

　　Demographic history can be divided into two major periods: a time of long, slow growth which extended from about 8000 B．C. till approximately 1650 A．D.. In the first period of some 9,600 years, the population increased from some 8 million to 500 million in 1650. Between 1650 and 1975, the population has increased from 500 million to more than 4 billion. And the population reached 6.2 billion throughout the world by the year 2000.One way to appreciate this dramatic difference in such abstract numbers is to reduce the time frame to something that is more manageable. Between 8000 B．C. and 1650, an average of only 50,000 persons was being added annually to the world's population. At present， this number is added every six hours. The increase is about 800,000,000 persons annually.

　　本文讲述的是人口增长的历史，从公元前8000年到当前人口的增长情况进行分析。

　　5．The underlined word “demographic” in Paragraph 1 means ________.

　　A．extinction of human

　　B．statistics of human population

　　C．death rate of human

【2017届高考北师大版英语二轮复习单元限时规范练：必修1 Unit 3《celebration》（含解析）】相关文章：

★ 【课堂新坐标】2017届高考英语（通用版）二轮复习书面表达专题训练：Ⅱ卷强化增分练 训练3（含解析）

★ 2014高考英语（新人教版）一轮基础训练（20）A、B卷（附答案或解析）

★ 【浙江专用】2014届高考英语一轮复习课时作业(十)必修2Unit 5《Music》

★ 【三维设计】2017版（江苏专用）二轮复习练习：选修8 Unit 4《Films and film events》课时跟踪检测A卷（含解析）

★ 2014高考英语（新人教版）一轮基础训练（2）A、B卷（附答案或解析）

★ 【三维设计】2017版（江苏专用）二轮复习练习：必修3 Unit 3《Back to the past》单元检测（含解析）

★ （全国通用）2014届高考英语一轮单元复习 限时强化训练五

★ （安徽专用）2014届高考英语一轮复习方案 作业手册（23）模块8 《Unit 23 Conflict》（含解析） 北师大版必修1

★ 2014届高考英语一轮复习课时作业(三十九)选修7Module 3《Literature》（外研版）

★ 【北师大版】2014届高考英语一轮复习指导课时作业：Unit 11 A卷 Word版含解析