2012的倒数是______.
∵2012×12012=1,
∴2012的倒数是12012.
故答案为:12012.
The number of students who took part in the competition last week ________ more than 1500.
A.reach
B.were
C.is
D.was
用一根机械效率为90%的杠杆将一个18Kg的物体提升50cm,则所做的有用功为 _________ J,总功为_________J(g取10N/kg)