不使点外力不大容易吧。用搋子http://baike.baidu.com/link?url=xDU8NFDhQPm0hLMQIDGJLc1e9PLS6_5KYY0OekSSak1D_REzKehDhGIO5F6ib6wlCCH3k6vrNSWIPGuw1jc9ROOed89aFhdvGoaOn7LPSVy试试。
