When he walks ______ my desk, he often knocks my books off the desk.

Jeff, clean your bedroom. Don’t be so .

Everyone knows that _____ sun is in the center of thesolar system（太阳系）

The rich man ______ much food______ the poor families during the hard time.

ing, the largest of the Ming Tombs, is atthe heart of Shisanling, with the other tombs _____ on either side of it.