有一构件的实际长度L=0.5m,画在机构运动简图中的长度为20mm,则画此机构运动简图时所取的长度比例尺μl为____()
A. 0.025m/mm
B. 25mm/m
C. 1:25
D. 25
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Yet even when the basic science of climate change has been accepted by almost all scientists, many others still seem to think that it is unfounded()
A. uninterested
B. unheard
C. unidentified
D. unsupported
用3,5-二硝基水杨酸定糖法测定还原糖含量时,使用的波长是()nm
A. 540
B. 600
C. 640
D. 500
紫外法可用来鉴定蛋白质的纯度,当蛋白质样品中核酸含量增加时,A280nm/A260nm的值将()
A. 增大
B. 减小
C. 不变
D. 说不准
Students have got into the spirit, waging competitions to boost recycling and slash energy use in dorms()
A. reduce
B. increase
C. decrease
D. promote