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【单选题】
When the traveler felt tired, he stopped ___.A.
drink
B.
to drink
C.
drinking
D.
drunk
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皮皮学刷刷变学霸
举一反三
【简答题】A．related B．concentrated C．entitled D．assigned
【单选题】Subjects are said to be assigned randomly when
A.
they are assigned to experimental and control groups from a sample which is representative of the larger population.
B.
they each have an equal chance of being assigned to either the experimental or control group.
C.
they are assigned to experimental and control groups so that the groups differ on some critical variable before the experiment begins.
D.
neither the experimenter nor the subject knows whether the subject is in the experimental or control group.
【简答题】液压泵是一种将机械能转换为液压能的能量转换装置。它为液压系统提供具有一定压力和流量的液体,是液压系统的一个重要组成部分。 构成液压泵的基本条件是什么?
【简答题】构成液压泵的基本条件是：
【简答题】A．conducted B．searched C．discussed D．assigned