A.7° B.8° C.9° D.10°
A.3.4m~3.7m B.2.4m~2.7m C.1.4m~1.7m D.0.4m~0.7m
A.有利于視線誘導(dǎo) B.緩沖能力大 C.對(duì)行車有壓迫感 D.可以重復(fù)使用