单项选择题
A．The water would come from the open cups. B．The water would spill all over their food C．Crams would float in the cups D．The cups would float in the air.
A．it was man' s first real invention B．all transportation depends on it C．every machine depends on it D．both B and C
A．round piece of stone B．heavy log C．piece of metal D．slice of log