可以看一下这个：

http://www.mscbsc.com/askpro/question.php?qid=5827

http://www.mscbsc.com/askpro/question.php?qid=8806

http://www.mscbsc.com/askpro/question.php?qid=9576

http://www.mscbsc.com/askpro/question.php?qid=13991