如何用VueJS2在HTML表格中显示对象键？

<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>

var app = new Vue({
  el: '#app',
  data: {
    users: [
      { id: 1, name: 'John', age: 25 },
      { id: 2, name: 'Jane', age: 30 },
      { id: 3, name: 'Bob', age: 35 }
    ]
  }
});

<div id="app">
  <table>
    <thead>
      <tr>
        <th>ID</th>
        <th>Name</th>
        <th>Age</th>
      </tr>
    </thead>
    <tbody>
      <tr v-for="user in users" :key="user.id">
        <td>{{ user.id }}</td>
        <td>{{ user.name }}</td>
        <td>{{ user.age }}</td>
      </tr>
    </tbody>
  </table>
</div>