在安装工程中,泵可按叶轮固定在轴上的相对位置、叶轮及托架的支撑方式不同,可分为()。
A.直联式泵
B.动力式泵
C.悬臂式泵
D.悬架式泵
参考答案:A, C, D
计算:(-1)2=______.
— "_______"
— "My father will be back in half an hour." [ ]
A. How long will your father be back?
B. How often will your father be back?
C. How soon will your father be back?
D. How far will your father be back?