—How clean the bedroom is!—Yes,I am sure that someone___ it.

—How clean the bedroom is!—Yes,I am sure that someone___ it.
—How clean the bedroom is!
—Yes,I am sure that someone___ it.
A.cleans B.cleaned C.has cleaned D.had cleaned—The light in his room is still on.Do you know ___
—In order to prepare for the coming exam.
A.if he works hard B.why he stays up so late
C.why is he so busy D.when he will stop working