frictions差距frictionn.摩擦；摩擦力；分歧friction cloth涂橡胶亚麻布friction spark摩擦火花friction ridge摩擦嵴friction wafer摩擦片friction tight利用摩擦力紧配合的friction field摩擦力界friction winch摩擦传动绞车friction cluth摩擦离合器friction power摩擦功率friction layer摩擦层,地表边界层