为什么在测试组件View的例子的时候没有出现预计结果

<!–pages/view_use/view/view.wxml–>

<view class=“section”>

 <view class=“section__title”>flex-direction: row</view>

 <view class=“flex-wrp” style=“flex-direction:row;”>

   <view class=“flex-item bc_green”>1</view>

   <view class=“flex-item bc_red”>2</view>

   <view class=“flex-item bc_blue”>3</view>

 </view>

</view>

<view class=“section”>

 <view class=“section__title”>flex-direction: column</view>

 <view class=“flex-wrp” style=“height: 300px;flex-direction:column;”>

   <view class=“flex-item bc_green”>1</view>

   <view class=“flex-item bc_red”>2</view>

   <view class=“flex-item bc_blue”>3</view>

 </view>

</view>