问题补充：
--Look! Someone the floor.
--Well, it wasn’t me. I went shopping just now.
A. had swept
B. has swept
C. was sweeping
D. is sweeping
答案：
A. had swept
(答案→)B. has swept
C. was sweeping
D. is sweeping
解析：句意：--看，有人已经擦过地板了。--哦，那不是我，我刚才去买东西去了。这里根据it wasn’t me.可知地板已经擦完，强调过去的动作对现在造成的影响。故选B。
