I cleaned the room for an hour

Our monitor cleaned the room an hour ago 改为否定句 ---Catherine,I have cleaned the room for you. I cleaned my room and studied for the math I waited for the train （for） over an hour. --Catharine,I have cleaned the room for you.--- Thanks.You _ i danced for an hour. I have already cleaned the room.(对cleaned the room提问） I’m going to the shop _____.A.for an hour B.after an hour C. The bus came after I for about half an hour The bus came sfter I --------- for about half an hour who cleaned the room? I heard someone play the piano in the music room an hour ago