单项选择题
A.Provides surface for applying force on machinery B.Provides landing surface for the sounding bob C.Absorbs machinery vibration D.Prevents valve stem over-travel
A.Wooden (lignum vitae) strips B.Hard rubber C.Resin bonded composition D.Bronze bushings
A.Brown conical tower with white horizontal band in center of light on black pier B.Red conical tower on brown cylindrical pier C.White octagonal house on brown cylindrical pier D.White conical tower,with brown band midway of height