Bootstrap4　モーダルが動かない

bootstrap4のサイトを見ながら記載してモーダルを動かそうとしたのですが、モーダルが表記されません。
一体なにが原因なのでしょうか。親切な方ご連絡お待ちしております。

HTML
1<!doctype html>
2<html lang="ja">
3  <head>
4    <!-- Required meta tags -->
5    <meta charset="utf-8">
6    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
7
8    <!-- Bootstrap <CSS -->
9    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
10    <link href="/font/css/open-iconic-bootstrap.css" rel="stylesheet">
11   
12    <link href="https://cdn.jsdelivr.net/gh/gitbrent/bootstrap4-toggle@3.6.1/css/bootstrap4-toggle.min.css" rel="stylesheet">
13    <script src="https://cdn.jsdelivr.net/gh/gitbrent/bootstrap4-toggle@3.6.1/js/bootstrap4-toggle.min.js"></script>  
14    <Link href="https://use.fontawesome.com/releases/v5.6.1/css/all.css" rel="stylesheet" />    
15 
16        </head>    
17 <body>
18     
19  <!-- Button trigger modal -->
20<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">
21  Launch demo modal
22</button>
23
24<!-- Button trigger modal -->
25<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">
26  Launch demo modal
27</button>
28
29<!-- Modal -->
30<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
31  <div class="modal-dialog" role="document">
32    <div class="modal-content">
33      <div class="modal-header">
34        <h5 class="modal-title" id="exampleModalLabel">Modal title</h5>
35        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
36          <span aria-hidden="true">&times;</span>
37        </button>
38      </div>
39      <div class="modal-body">
40        ...
41      </div>
42      <div class="modal-footer">
43        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
44        <button type="button" class="btn btn-primary">Save changes</button>
45      </div>
46    </div>
47  </div>
48</div>
49     
50     
51     
52        </body>
53      </html>