摘要: ``` > 1+NA [1] NA > NA==1 [1] NA > c(NA,1:50) [1] NA 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 [32] 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47... 阅读全文
posted @ 2016-04-21 01:38 li_volleyball 阅读(335) 评论(0) 推荐(0) 编辑