【题目】—Look！Every desk and every chair in the classroom .
—Oh，it must have taken you lots of time.
A. is cleaned B. are cleaned
C. has been cleaned D. have been cleaned
在线课程【答案】C
【解析】考查主谓一致及时态。and连接的并列主语是单数概念，且前面有every，each，no等修饰时，谓语动词用单数。由语境可知此处应用现在完成时，表已经完成的动作。