When a vehicle changes lane, the driver should  turn on the turn signal in advance, observe,keep a safe distance and enter the new lane. Answer:  √

A vehicle running on an expressway may frequently change lanes. Answer:  ×

When a vehicle runs on an expressway at the speed of 100km/h,the safe distance from vehicle ahead is 100m. Answer:  √  

When braking on a muddy road, the tires can easily spin or drift and cause traffic accidents. Answer:  √