正确答案B
WF-mgh=0 WF1/WF2=h1/h2=2/3
什么情况下才能选A
WF-mgh-Wf=0 WF=mgh+Wf
mgh1+wf1=mgh2+wf2 wf1/wf2=3/2
当摩擦力做功 wf1:wf2=3:2 时 选A