I have multiselect check box drop down field as below. when the user selects the option the selected value is getting displayed in field and placedholder getting hiddden.

I do not want this behavior to happen if user selects the option the values should be displayed in the field

<mat-form-field appearance="outline">
   <mat-select multiple placeholder="vechile">
      <mat-option value="1"> Car</mat-option>
      <mat-option value="2"> Bike</mat-option>
   </mat-select>
</mat-form-field>