linear inequality in two variables

例句：

1. 1.The path is linear and easy to follow.
   这条路线是直线的，很容易跟随。
2. 2. The data is linearly proportional to the input.
   数据与输入成正比例关系。
3. 3.The book is linearly arranged in chapters.
   这本书按章节线性排列。