selected - 垫子自动完成选定的值

Question

   <mat-form-field class="example-full-width">
   <mat-label>Adjustment nominal account</mat-label>
   <input type="text" placeholder="Adjustment nominal account" aria-label="Number" matInput
   [formControl]="myControl" [matAutocomplete]="nominal" [(value)]="selectedVal">
   <mat-autocomplete #nominal="matAutocomplete">
   <mat-option *ngFor="let option of options" [value]="option"> {{option}} </mat-option>
   </mat-autocomplete>
   </mat-form-field>

请帮我：

如何在 mat-auto-complete 中添加默认选定值？