第三部分 阅读理解（共20小题：每小题2.5分，满分50分）
阅读下列短文，从每题所给的四个选项A、B、C、D四个选项中，选出最佳选项。
Today, as in every other day of the year, more than 3000 U.S. adolescents will smoke their first cigarette on their way to becoming regular smokers as adults. During their lifetime, it can be expected that of these 3000 about 23 will be murdered, 30 will die in traffic accidents, and nearly 750 will be killed by a smoking-related disease. The number of deaths attributed to cigarette smoking outweighs all other factors, whether voluntary or involuntary, as a cause of death.
Since the late 1970s, when daily smoking among high school seniors reached 30 percent, smoking rates among youth have declined. While the decline is impressive, several important issues must be raised.
First, in the past several years, smoking rates among youth have declined very little. Second, in the late 1970s, smoking among male high school seniors exceeded that among female by nearly 10 percent. The statistic is reversing. Third, several recent studies have indicated high school dropouts have excessively high smoking rates, as much as 75 percent.
Finally, though significant declines in adolescent smoking have occurred in the past decade, no definite reasons for the decline exist. Within this context, the National Cancer Institute (NCI) began its current effort to determine the most effective measures to reduce smoking levels among youth.
36. According to the author, the deaths among youth are mainly caused by __________.
A. traffic accidents                                   B. smoking-related disease
C. murder                                                 D. all of these
37. Every day there are over ______ high school students who will become regular smokers.
A. 750                         B. 23                    C. 30                    D. 3000
38. By “dropout” the author means __________.
A. students who failed the examination        B. students who left school
C. students who lost their way                    D. students who were driven out of school
39. The reason for declining adolescent smoking is that __________.
A. NCI has taken effective measures           
B. smoking is prevented among high school seniors
C. there are many smokers who have died of cancer          
D. none of these
40. What is implied but not stated by the author is that __________.
A. smoking rates among youth have declined very little     
B. there are now more female than male smokers among high school seniors
C. high smoking rates are due to the increase in wealth
D. smoking at high school is from low socio-economic backgrounds