我无法通过终端上传引导程序

Question

我没有正确导入引导程序，我也不知道为什么。

我运行npm save bootstrap并将文件导入到我的index.js文件中，  每个文档。样式仍然不适用。

Index.js

import React from "react";
import ReactDOM from "react-dom";
import "./index.css";
import App from "./App";
import * as serviceWorker from "./serviceWorker";
import 'bootstrap/dist/css/bootstrap.min.css';

import { BrowserRouter as Router } from "react-router-dom";
ReactDOM.render(

    <Router>
      <App />
    </Router>,

  document.getElementById("root")
);


serviceWorker.unregister();

NavBar.js

import React, { Component } from "react";
import { Link } from "react-router-dom";
import logo from "../logo.svg";

export default class Navbar extends Component {
    render() {
      return (
        <nav className="navbar navbar-expand-sm  bg-primary navbar-dark px-sm-5">
          {/* 
  https://www.iconfinder.com/icons/1243689/call_phone_icon
  Creative Commons (Attribution 3.0 Unported);
  https://www.iconfinder.com/Makoto_msk */}
          <Link to="/">
            <img 
            src={logo} 
            alt="store" 
            className="navbar-brand"/>
          </Link>

          <ul className=" navbar-nav align-items-center">
            <li className="nav-item ml-5">
            <Link to="/" className="nav-link">
            Products
            </Link>
            </li> 
          </ul>
        </nav>
      );
    }
  }