css3 左两右一布局

Question

flex布局怎么弄这样的两个在左边 一个在右边的布局

<div class="box">
    <div class="l1">左1</div>
    <div class="l2">左2</div>
    <div class="r1">右1</div>
</div>

Answer 1

.r1{margin-left: auto}