在角度选择中选择特定的默认选项

Question

Exp是我的下拉列表，在浏览器中正确显示。 我想在exp select中选择expense.expenseType.param作为默认选项

<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.6.5/angular.js"></script>
<div ng-repeat="expense in expenses">
  <div>
    expense Type {{exp[0].id}} {{exp[0].param}}<br> expense {{expense.expenseType.id}} {{expense.expenseType.param}}<br/>
    <label>Expense Type <a href="#"  class="label label-primary" ng-click="expenseType = true">add category</a></label>
    <select name="id" ng-model="expense.id" ng-options="e.id as e.param for e in exp track by expense.expenseType.param" class="form-control" ng-required="true">
    </select>
  </div>
</div>

打印时的结果

费用类型53 zz（显示拳头费用类型）

费用39购物

我想在选择选项中默认选择购物。如何做到这一点