Two ________ thirds of the work ________ already finished．I don't think you'll have to wait long．
A.areB.isC.to beD.being在线课程B
前半句是一句完整的句子，所填的空格应为谓语动词，故C项和D项均不对。如果不可数名词前有分数，百分比等修饰，我们谓语动词用单数，这里的名词work是不可数名词。