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【单选题】
Double-blind experiments are used to make sure that _________.A.
the participants will continue taking the treatment
B.
the participants won't tell the researchers which treatment they think they are taking
C.
the researchers will always give the best treatment to participants
D.
the researchers won't accidentally give hints to participants about which treatment they are getting
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【简答题】cater to/for
【单选题】When Fred told Pearman to call if he was serious, he meant if ______.
A.
Pearman was really hard-working
B.
Pearman was really interested in washing windshields
C.
Pearman's conditions were truly serious
D.
Pearman was really looking for a job
【简答题】水处理方法归纳起来可分为