请技术人员解答，flex-direction: row 无效

下面是官方的例子：为什么flex-direction: row 也不能横排了呢？搞了一个星期了，都不能解决。请技术人员解答！
<view class="section">
  <view class="section__title">flex-direction: rowview>
  <view class="flex-wrp" style="flex-direction:row;">
    <view class="flex-item bc_green">1view>
    <view class="flex-item bc_red">2view>
    <view class="flex-item bc_blue">3view>
  view>view><view class="section">
  <view class="section__title">flex-direction: columnview>
  <view class="flex-wrp" style="height: 300px;flex-direction:column;">
    <view class="flex-item bc_green">1view>
    <view class="flex-item bc_red">2view>
    <view class="flex-item bc_blue">3view>
  view>view>

都提问好几天了，怎么就没有人能帮解决一下呢？我很急。https://developers.weixin.qq.com/blogdetail?action=get\_post\_info&docid=d86e12ed81a4ea105df5eb3dcb051093&token=544777948&lang=zh\_CN