对括号里的提问
1.ThestudentsinClass1,Grade7willgoonatriptoBeijing(bytrain)
____________thestudentsinClass1,Grade7willgoonatriptoBeijing
2.Thechildrenusuallyknockon(theirneighbours'doorsatHalloween.)
____________dothechildrenusuallyknock_______atHalloween?