Mom,where is David?—He is working _____ that difficult math problem in his room.[ ]
_______ do the students have P.E.?—Twice a week. [ ]
He is too tired. He doesn’t want to do_______.
Is Miss White________ English teacher, Maria?–No,she teaches________ geography.
Is Mo Yan, the Nobel Prize winner, ______ best writer in China?—It’s hard to say. But he is really ______ very good writer.