A、2,000. B、4,000. C、7000 D、9000 B选项的内容表明，本题与数字有关，故听音时应留意与数字相关的信息。敦子博士和她的同事用统计学的方法在之前的一些小型研究的基础上进行了一次大规模的研究，她们找来了4，000名有口腔癌和咽喉癌的病

Coffee is one of the world’s most widely-enjoyed beverages. Flavor aside, scientists have recognised it as a complex blend of chemical compounds with potential health effects, both good and bad. Now, new research suggests that if you drink enough coffee, it might help you avoid certain kinds of cancer.
    Dr. Mia Hashibe of the University of Utah School of Medicine was interested in the link between coffee drinking and certain cancers of the head and neck. Researchers have looked into this before, but without reaching any firm conclusions.
    "There were a few studies, but the findings were not consistent across the studies," she said, "so this finding from our current study was quite a surprise. We didn’t really have any expectation of which direction it could go into." To sort out the confusion, Hashibe and her colleagues used statistical techniques to, in effect, make one big study out of the previous smaller studies.
    "We combined data across nine individual studies, so we have a lot more power than previous studies that looked at this. And we included 4,000 cancer patients who have cancer of the oral cavity and pharynx throat. And then 9,000 controls, so controls are people who do not have cancer."
    Those studies — in Europe and the United States — found that people who drank a lot of coffee were less likely to develop cancers of the mouth and throat.
    In an interview via Skype, Mia Hashibe said there was a weak link between cancer risk and drinking decaffeinated coffee, but it wasn’t statistically significant.
Questions 16 to 18 are based on the passage you have just heard.
16. What does the new research show?
17. How many cancer patients participated in Hashibe’s study?
18. What did the studies carried out in Europe and the United States find?