qyj8888 发表于 2010-3-19 11:28 
1# zoumingwang2004
cards; 是读入下面数据的意思
有三个变量,两个观测值
因为是以C 为分隔符,读入
'Cards' means below is data. 'Cards' has a long history.
I give a link here. You will undstand it after read the link.
http://en.wikipedia.org/wiki/Punched_card