（一）Question 1 to 5 are based on the following passage:Adverse (不良的) drug reactions may cause the deaths of over 100,000 U.S. hospital patients each year, making them a leading cause of death nationwide, according to a report in the journal of the American Medical Association.The incidence（发生率）of serious and fatal adverse drug reaction (ADRs) in US hospitals was found to be extremely high, say researchers at the University of Toronto in Ontario, Canada.They carried out an analysis of 39 ADR-related studies at US hospital over the past 30 years and defend an ADR as “any harmful, unintended, and undesired effect of a drug which occurs at doses（剂量）used in humans for medical treatment.”An average 6.7% of all hospital patients experience an ADR every year, according to the researchers, they estimate that “in 1994，overall 2,216,000 hospital patients had serious ADRs and 106,000 had fatal ADRs.” This means that ADRs may rank the fourth single largest cause of death in America.The control of ADR also means appending more money. One US study estimated the overall cost of treating cause of death in America. The David Bates of Brigham and women’s hospital in Boston, Massachusetts, believes that healthcare workers need to pay more attention to the problem, especially since many ADRs are easily preventable. “When a patients develops an allergy（过敏症）or sensitivity, it is often not recorded,” Bates notes，“and patients receive drug to which they have known allergies or sensitivities with disturbing frequency.” He believes special computerized systems-still work –in –progress at many of the nation’s hospital-should help cut down the frequency of these type of errors.

A. the American Medical Association
Brigham and women’s hospital in Boston
C. doctors at an American hospital
D. researchers at a Canadian university