送交者: 小机灵 于 June 04, 2003 14:05:48:
回答: 你改名叫小机灵吧:) 由 呆头呆脑 于 June 04, 2003 13:02:27:
You start with burning both ends of the first rope and one end of the second rope. When the first rope burned out you start burning the other end of the second rope. It will take 15 minutes to burn out the second half of the second rope.