wx:key一直报警怎么填写啊？

[Violation] ‘setTimeout’ handler took 91ms

[sitemap 索引情况提示] 根据 sitemap 的规则[0]，当前页面 [pages/index/index] 将被索引

[WXML Runtime warning] ./pages/index/index.wxml

 wx:key=“{{index}}” does not look like a valid key name (did you mean wx:key=“index” ?)

   5 |       <view class=“list-scroll-view”>

   6 | 

>  7 |         <view wx:for=“{{list}}” wx:key=“{{index}}” wx:for-item=“course” wx:for-index=“i” class="course-card ">

     |          ^

   8 |           <view>

   9 |             <image src=“{{course.coverPath}}” mode=“widthFix”></image>

  10 |           </view>