Lines 82 and 83 draw a dotted line at the top and halfway down the Y-axis. This simply makes the graph easier to read.

第82和83行在y轴的顶端和中间各划一条水平虚线，这样做只是为了让查看图时更方便。

youdao

Lines 82 and 83 draw a dotted line at the top and halfway down the Y-axis. This simply makes the graph easier to read.

第82和83行在y轴的顶端和中间各划一条水平虚线，这样做只是为了让查看图时更方便。

youdao