Angular 2+和Observables：无法绑定到“ ngModel”

Question

编辑：更新的Plunkr：http：//plnkr.co/edit/fQ7P9KPjMxb5NAhccYIq？p = preview这部分工作：<div *ngFor="let entry of entries | async">  Label: {{ entry.label }}<br>  Value: {{ entry.value }}</div>但是选择框出现问题，错误消息是：无法绑定到“ ngModel”，因为它不是“ select”的已知属性整个组件：//our root app componentimport {Component} from '@angular/core';import {NgFor} from '@angular/common';import {HTTP_PROVIDERS, Http} from '@angular/http';import 'rxjs/Rx';import {Observable} from 'rxjs/Rx';@Component({  selector: 'my-app',  providers: [HTTP_PROVIDERS],  template: `  <select [(ngModel)]="selectValue" name="selectValue">    <option *ngFor="let entry of entries | async"     [value]="entry.value">{{entry.label}}</option>  </select>    <div *ngFor="let entry of entries | async">      Label: {{ entry.label }}<br>      Value: {{ entry.value }}    </div>  `,  directives: [NgFor]})export class App {  entries: any = {};  selectValue:any;  constructor(private _http: Http) {    this.entries = this._http.get("./data.json")                            .map(res => res.json());  }}和data.json[  {    "timestamp": 0,    "label": "l1",    "value": 1  },  {    "timestamp": 0,    "label": "l2",    "value": 2  },  {    "timestamp": 0,    "label": "l3",    "value": 3      }]