线性布局 LinearLayout 概念篇讲义
2017 Android 中文开放式课程 目录
https://goo.gl/Ti8mGA
影片教学：
https://goo.gl/J141gC
https://imgur.com/tq4Yx7p.png
https://imgur.com/IFXFdJs.png
https://imgur.com/SSpanlY.png
https://imgur.com/MtCfK1E.png
https://imgur.com/hl65eJL.png
https://imgur.com/3efaupV.png
https://imgur.com/QNx2G5t.png
https://imgur.com/aCYm3bN.png
https://imgur.com/O1OtRFZ.png