A

People used to 1.be_conveyed(convey) from one place to another by buses and trains.However£¬nowadays more  and more families have their own cars£¬which 2.speeds(speed)  up the development of our national economy and meanwhile results in more traffic jams.What's worse£¬some drivers violate traffic rules£¬such  as drunk  and  driving and speaking on their phones while 3.driving(drive)£¬which leads to more accidents and more deaths 4.arising(arise) from the accidents.

Only when people have put 5.through the pain can they realize that it is up to them all 6.to_ensure(ensure) that roads are smooth.At the same time£¬more and more people begin to take buses to go out£¬which can pick up and drop off people at different stops in the route.