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【单选题】
在铰链四杆机构中,若两个连架杆中一个为曲柄,另一个为摇杆此种四杆机构即称为( )。A.
曲柄摇杆机构
B.
双曲柄机构
C.
双摇杆机构
D.
摇杆机构
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【简答题】The reading of all good books is like a conversation with the finest men of the past centuries.
【单选题】Over the past century, the composition of the human gene pool ______ appreciably.
A.
did not change
B.
has not changed
C.
was not changed
D.
had not changed
【单选题】—Why ______ you _______ give such a talk? —Well, I've applied for this job. They've asked all the applicants to give a talk as part of the selection process. [ ]
A.
don't; have to
B.
had; had to
C.
are; used to
D.
have; got to
【单选题】为研究新药A治疗胃病疗效，在某医院选择40例胃病患者，随机分成实验组和对照组，实验组用药A，对照组用公认有效的药B。这种对照在实验设计中称为（ ）
A.
实验对照
B.
空白对照
C.
标准对照
D.
历史对照
【单选题】研究新药A治疗胃病疗效,在某医院选择40 例胃病患者,随机分成实验组和对照组,实验组用药 A,对照组用公认有效的药B。这种对照在实验设计中称为( )
A.
实验对照
B.
空白对照
C.
标准对照
D.
历史对照
【简答题】补全对话. S:I've just been to the English Corner: T: 1 Did you talk with Ben and Andy? S: 2 And I'm not sure if they understood me. T: 3 You have had a good start. S: But I'm afraid of mistakes whe...
【简答题】在重力场中均质物体的重心与物体的重力无关，只取决于物体的形状，即均质物体的重心就是其几何形体的中心，简称为__。
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【简答题】The reading of all good books is like a conversation with the finest men of the past centuries.