import and use box component

vuex_demo1/src/App.vue

@@ -3,17 +3,21 @@
     <my-add></my-add>
     <p>-----------------------------------------</p>
     <my-sub></my-sub>
+    <p>-----------------------------------------</p>
+    <box></box>
   </div>
 </template>
 
 <script>
 import add from './components/add.vue'
 import sub from "./components/sub.vue"
+import box from './components/box.vue'
 
 export default {
   components:{
     "my-add":add,
-    "my-sub":sub
+    "my-sub":sub,
+    box
   },
   data(){
     return{