A:①②③④
B:①②③
C:②③④
D:③④
The drivers have to _______ the traffic rules and control themselves if they want to be safe on the road.
一个历史事实可以由若干事件构成,事件又可以由若干小事件构成,由此可以排出一系列事件的等级或层次。下列选项符合上述说法的是( )