678. The higher the driving speed, the driver\'s reaction distance is (A) longer (B)shorter (C) unchanged.

686.Which of the following is NOT a correct behavior when riding a motorcycle?\(A) Yield to vehicles outside the roundabout when passing through it\ (B) Mostgas station exits have no traffic signals; drivers should slow down and payattention to vehicle movements\ (C) When riding in alleys, reduce speed anduse mirrors to check for oncoming vehicles