不能将名称空间用作离子类型

Question

我是离子应用程序开发的新手，我知道这是一个非常基本的问题，但是有一天以来，我一直在面对这一问题，我已经从互联网上下载了一个应用程序，当我打开代码显示错误消息时，即无法使用命名空间类型为ionic ，为什么我收到此错误消息，请问可以对我有帮助吗

代码：

import { Component, ViewChild } from '@angular/core';
import { Platform, MenuController, Nav, App } from 'ionic-angular';
import { StatusBar } from '@ionic-native/status-bar';
import { SplashScreen } from '@ionic-native/splash-screen';
import { LearnFeedPage } from '../pages/learn-feed/learn-feed';


@Component({
  selector: 'app-root',
  templateUrl: 'app.html'
})
export class MyApp {
  @ViewChild(Nav) nav: Nav;

  // make LearnFeedPage the root (or first) page
  rootPage: any = LearnFeedPage;
  pages: Array<{title: string, component: any, params: any}>;

  constructor(
    platform: Platform,
    statusBar: StatusBar,
    splashScreen: SplashScreen,
    public menu: MenuController,
    public app: App
  ) {
    platform.ready().then(() => {
      // Okay, so the platform is ready and our plugins are available.
      // Here you can do any higher level native things you might need.
      statusBar.styleDefault();
      splashScreen.hide();
    });