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【单选题】
某学者为探讨某药物对某病的疗效,选取了120例该病患者,随机分为服用该药的治疗组和服用标准疗法的对照组,随访观察时,观察者与患者均不知道两组接受的措施,1个月后观察疗效,结果治疗组的60名患者中有40人有效,对照组中的60人中有5人有效。经统计学检验,两组差异具有统计学意义。该研究采用的盲法为:A.
没有盲法
B.
C.
D.
三盲
E.
不清楚
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反馈参考答案：
举一反三
【简答题】A．essential B．elementary C．necessary D．principal
【单选题】How is the principal amount of an interest-only loan repaid?
A.
The principal is forgiven over the loan period so does not have to be repaid.
B.
The principal is repaid in equal increments and included in each loan payment.
C.
The principal is repaid in a lump sum at the end of the loan period.
D.
The principal is repaid in equal annual payments.
【单选题】There is _______ wrong with your watch. Let me check it.
A.
something
B.
everything
C.
nothing
D.
anything
【单选题】The coefficient vector of the principal component expression is the eigenvector of _______________.
A.
the covariance matrix of original variables
B.
the covariance matrix of principal components
【单选题】The principal-Agent problem is mainly because
A.
it is costly and hard for the principal to monitor the agent.
B.
the principal and agent have different incentives
C.
some of the principals have the incentive to take a free-ride of other principals' monitoring
D.
all of the above
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