在电轧刀的铭牌上,标定的电压值有()几种。
A.220V、110V、36V
B.220V、24V、15V
C.220V、36V、24V
D.110V、36V、24V
参考答案:C
—We expected you yesterday.
—I'm sorry, I you to say that I couldn't be here until today. [ ]
A. must have called
B. would be calling
C. could have been calling
D. should have called
某工地上,一架起重机将质量为2t的货物以0.1m/s的速度匀速提升10m后又水平匀速移动5m,求:
(1)在整个过程中,起重机对货物做的功;
(2)在货物上升的过程中,起重机对货物做功的功率。(g取10N/kg)