我几乎做到了，但有一个小细节卡住了。我似乎不能让所选汽车制造商的“汽车型号”的“名称”属性实际上显示在选择菜单上。目前，它似乎显示了正确的选项数量，但选项明显是空白的。下面是我的代码，以帮助更好地解释...

$scope.carMakes = [
    {
        name: 'Honda',
        models: [{name:'Accord'}, {name: 'Civic'}, {name: 'CRX'}]
    },
    {
        name: 'Toyota',
        models: [{name:'Camry'}, {name: 'Forerunner'}]
    }
];

   <div class="input-group">
        <label>Vehicle Make</label>
        <select id="carMake" ng-model="carMake" ng-options="carMake as carMake.name for carMake in carMakes track by carMake.name">
            <option value="">All</option>
        </select>
    </div>
    <div class="input-group carModels">
        <label>Vehicle Model</label>
        <select id="carModel" ng-model="carMake.model" ng-options="carMake.model as carMake.model.name for carMake in carMake.models">
            <option value="">All</option>
        </select>
   </div>

有人能告诉我为什么尽管显示了carModel选择选项，但没有显示“name”吗？谢谢！