液体沸腾时,汽泡内的压力大于汽泡外液体的压力,主要由于下列哪个因素造成的?()
A.传热温差
B.表面张力
C.浮升力
D.重力
参考答案:B
— What's Mr Lai selling to Eric?
— ____ selling ____ a newspaper. [ ]
A. His, him
B. He's, her
C. She's, her
D. He's, him
宋元是我国古代科技发展的高峰时期,阅读下列图片,回答问题。
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