The limit switches on a ships survival-craft winch system（）.

A.stop the winch just before the craft reaches the final stowage position

B.limit the amount of cable on the drum

C.limit the ascent rate

D.stop the winch in case the craft weighs too much

桥梁标，设在桥梁中央处，标明桥梁编号、中心里程和长度。