6、etoCanada.A.needn'tB. mustn’tC.mustD. can’tBCD4. — Someone is knocking at the door.— Who ______ it be at this hour of day?A. mayB. canC. mustD. should5. —You____behappywiththestrongpublicsupportyou'vereceived.—Yes,you'reright.I'mreallyexcited.A. mayB. canC. mustD.needBC6. Johnson ______ be a poli
7、ceman. He is much tooshort.A. mayB. mustn’tC. shouldD. can’tDExercisesItisdangerous.You______keepout!Thesestairsarenotsafe.You_______usethem.Therocksarefallingdown.You_____gethit.Theriveristoodeep.You_______swim