角异常:不能绑定到'ngForIn'，因为它不是已知的本机属性

What am I doing wrong?

我做错了什么?

import {bootstrap, Component} from 'angular2/angular2'@Component({  selector: 'conf-talks',  template: `<div *ngFor="let talk in talks">     {{talk.title}} by {{talk.speaker}}     <p>{{talk.description}}   </div>`})class ConfTalks {  talks = [ {title: 't1', speaker: 'Brian', description: 'talk 1'},            {title: 't2', speaker: 'Julie', description: 'talk 2'}];}@Component({  selector: 'my-app',  directives: [ConfTalks],  template: '<conf-talks></conf-talks>'})class App {}bootstrap(App, [])import {boot