D．development of human population

　　答案：B　词义猜测题。根据单词所在的句子中compare... to“a long, thin powder fuse that burns steadily and hesitatingly until it finally reaches the charge and explodes”并结合文章话题，可知。

　　6．Which of the following demographic growth patterns is most similar to the long thin powder fuse?

　　A．A slow growth for a long time and then a period of rapid, dramatic increase.

　　B．Too many people on earth and a few rapid increases in the number added each year.

　　C．A virtually stable or slightly decreasing period and then a sudden explosion of population.

　　D．A long period when death rates exceed birthrates and then a short period with higher fertility and lower mortality.

　　答案：A　细节理解题。导火线开始平稳燃烧，到最后会达到引爆点而爆炸，而人口的发展亦是如此。

　　7．During the first period of demographic history, societies were often in danger of extinction because ________.

　　A．only one in ten persons could live past 40

　　B．our ancestors had little enthusiasm for more children

　　C．there was higher mortality than fertility in most places

　　D．it was too dangerous to have babies due to the poor conditions

　　答案：C　细节理解题。根据第二段“because death rates could exceed their birthrates”可知。

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