Prolonging Human Life
    1.题目：The writer believes that the population explosion results from
    答案：C） a decrease in death rates.
    2.题目：It can be inferred from the passage that in hunting and gathering cultures
    答案：B） infants could be left dead in times of starvation.
    3.题目：According to the passage， which of the following statements about retired people in the United States is true？
    答案：A） Many of them have a very hard life.
    4.题目：In Paragraph 3， the phrase “this need” refers to
    答案：D） the need take care of sick and weak people.
    5.题目：Which of the following best describes the writer's attitude toward most of the nursing homes， and convalescent hospitals？
    答案：D） Critical.
    速记口诀：
    延长人类生命
    1.人口膨胀死亡减 ____________________
    2.狩猎文化婴儿死 ____________________
    3.退休老人生活难 ____________________
    4.照顾病弱是需要 ____________________
    5.作者态度是批评 ____________________