Every possible means ________, but the teacher as well as the students ________ found a solution to the problem yet
A.has been tried; hasn’tB.has tried; haven’tC.have tried; haven’tD.have been tried; hasn’t在线课程A
考查主谓一致。means单复同形，与every修饰，谓语动词用单数；as well as连接两个主语，谓语动词与前一个主语保持一致，故选A。