分页标题
2011-09-15 19:38:00   来源：作文地带    双击单词自动翻译

　　(A) In the middle of the nineteenth century, the population of North America was significantly smaller than it is today.

　　(B) Most of the gains in life expectancy in the last 150 years have come from reductions in the number of infants who die in their first year of life.

　　(C) Many of the people who live to an advanced age today do so only because of medical technology that was unknown in the nineteenth century.

　　(D) The proportion of people who die in their seventies is significantly smaller today than is the proportion of people who die in their eighties.

　　(E) More people in the middle of the nineteenth century engaged regularly in vigorous physical activity than do so today.

（责任编辑：申月月）