来自陈刚勇的问题
We----onitforseveralhoursbutwehavenotyetreachedanyconclusionA.workB.areworkingC.havebeenworkingD.havebeenworked
We----onitforseveralhoursbutwehavenotyetreachedanyconclusion
A.workB.areworkingC.havebeenworkingD.havebeenworked

