main.ts：

import { bootstrap } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppComponent,environment } from './app/';
import { APP_ROUTER_PROVIDERS } from './app/routes';
import {HTTP_PROVIDERS} from '@angular/http';
import {ServiceProvider} from "./app/providers/app.service.provider"

if (environment.production) {
  enableProdMode();
}
bootstrap(AppComponent,[ServiceProvider,APP_ROUTER_PROVIDERS,HTTP_PROVIDERS]);

routes.ts：

import {provideRouter,RouterConfig} from '@angular/router';
import {AppComponent} from "./app.component";
import {ReportDetailComponent} from "./component/AppReportDetailComponent";
import {ReportsListComponent} from "./component/AppReportListComponent";
import {ReportCreateComponent} from "./component/AppReportCreateComponent";


export const routes:RouterConfig = [
    {
      path: 'reports',children: [
        {path: ':id',component: ReportDetailComponent},{path:'',component: AppComponent },{path: 'create',component: ReportCreateComponent},{path: 'list',component: ReportsListComponent},]
    }
  ];
export const APP_ROUTER_PROVIDERS = [provideRouter(routes)];

app.component：

import {Component,OnInit} from '@angular/core';
import {ReportNavComponent} from "./component/AppReportNavComponent";
import { ROUTER_DIRECTIVES } from '@angular/router';
@Component({
  moduleId: module.id,selector: 'app-root',templateUrl: 'tpl/app.component.html',styleUrls: ['app.component.css'],directives: [ROUTER_DIRECTIVES,ReportNavComponent]

})
export class AppComponent {
  constructor() {
  }
}

app.component.html：

<report-nav></report-nav>
<router-outlet></router-outlet>

和最后一个AppReportNavComponent.ts：

import {Component} from "@angular/core";
import {ROUTER_DIRECTIVES} from '@angular/router';
@Component({
  selector: "report-nav",directives: [ROUTER_DIRECTIVES],template: `<nav>
  <a [routerLink]="['/list']">List</a>
  <a [routerLink]="['/create']">Create new</a>
</nav>`
})

export class ReportNavComponent {
  constructor() {
  }
}

如果我去/报告我应该看到两个链接“列表”和“创建”
但是在app-root标签里面我看到了辅助app-root标签(在图片上)
screenshot
我的问题是：为什么？