Einstein’s theory, which was doubted by most scientists at first___out to be correct in the end.

A．proved

B．was proved

C．turned

D．tested

用一动力臂是阻力臂5倍的杠杆，在5s内用60N的力，把240N的重物举高0.2m，则动力做功的功率是________ W，杠杆的机械效率为________ 。