圆形或矩形管道与下方给水管道或铸铁管道交叉且同时施工时，加设套管或管廓，套管、管廓的内径不应小于被套管道外径()。
A. 100mm
B. 200mm
C. 300nlm
D. 400mm
【C10】
A. synthesize
B. enhance
C. mishandle
D. counteract
【C13】
A. cautionary
B. debatable
C. retrospective
D. sensitive
Researchers should base their decisions on______.
A. immediate economic profits
B. long-term market potential
C. the value of knowledge
D. the prospect of their universities
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