填空。
①You mustn't walk around during landing. A. On a bus
②You mustn't talk to the driver. B. On a train
③You must wear a helmet . C. On a bike
④You must wear a seatbelt. D. On a car
⑤You mustn't put your head out of the window. E. On a plane
⑥You must wear a lifejacket. F. On a boat