給li標簽添加ng-repeat指令后，ng-mouseenter="show = true" ng-mouseleave="show = false"居然不起作用，為什么啦？求解？代碼如下：<ul class="im-dropdown-ul">    <li ng-repeat='x in provinceArr' ng-mouseenter="show = true" ng-mouseleave="show = false">     <span><input type="checkbox"><span>{{x}}</span></span></li></ul><div ng-show="show">Hello!</div>