单项选择题
A.Were there loss of energy by friction B.Since there be loss of energy by friction C.Were there no loss of energy by friction D.Should be no loss of energy by friction
（） the bodies are, （） the friction will be.A.The smooth...
单项选择题（） the bodies are, （） the friction will be.
A.The smoother；the greater B.Smoother；less C.The rougher；the greater D.rougher；greater
Convection is the principal means （） temperature is equ...
单项选择题Convection is the principal means （） temperature is equilibrated in liquids and gases.
A.in which B.on which C.by which D.from which
If you （） the equipment more carefully before sail, we ...
单项选择题If you （） the equipment more carefully before sail, we （） so much trouble now.
A.examined；are not having B.had examined；would not have C.had examined；would not have had D.should examine；would not have
