Advertising first became important in the late 15th century, __ the merchants of the rapidly growing cities and towns needed a way to tell people __ their goods could be bought.
【简答题】盘式制动器的检查,下面哪一种说法是正确的?( ) A .检查制动器衬块的厚度,如果外衬块比规定的厚度厚,就没有必要检查内衬块 B .检查制动衬块,确认它的厚度不低于规定 值 ,且内外衬块的厚度没有大的差别 C .检查 转子盘 ,如其外表没有出现任何磨损或损坏,那么其内表面也是正常 D .检查盘转子和衬块之间的间隙,踩下制动器踏板数次,确认盘不转动