单选题 When Edison died, it was proposed that the Americans ______ all power in their homes, streets and factories for several minutes in honor of this great man.
A. turn off B. turned off
C. must turn off D. would have turned off

【正确答案】 A
【答案解析】[解析] 虚拟语气题。It is/was proposed that...其后的从句用虚拟语气，动词形式为“should+动词原形”，should可省略。