`flex-flow`属性是`flex-direction`属性和`flex-wrap`属性的简写形式，默认值为`row nowrap`。 ~~~css .box { flex-flow: <flex-direction> || <flex-wrap>; } ~~~ ~~~html <div class="box"> <div class="box-item">1</div> <div class="box-item">2</div> <div class="box-item">3</div> <div class="box-item">4</div> <div class="box-item">5</div> <div class="box-item">6</div> <div class="box-item">7</div> </div> ~~~ ~~~css .box { display: flex; flex-flow: row wrap-reverse; background-color: white; } .box-item { width: 200px; height: 200px; line-height: 200px; vertical-align: middle; margin: 5px; background-color: #ffd200; font-size: 100px; color: white; text-align: center; } ~~~