Angular ngIf在子组件中的角度

我正在尝试在我的angular应用程序中的子组件中实现*ngIf。我想根据输入字段的formControlName值使用它。我只想在formControl值与给定值匹配时显示它。我该怎么做呢。请引导我

父组件HTML

<form class="parentForm" [formGroup]='parentForm'>
  <div class="col-md-12">
    <div class="row">
      <div class="col-md-12">
   <input class="" type="text" placeholder=" info" formControlName="test0">
   </div>
      </div>
         </div>
  <app-child [childForm]="parentForm.controls.childForm"></app-child>
</form>

<form  [formGroup]='childForm'>
  <div class="col-md-12" >
    <div class="row">
      <div class="col-md-12" *ngIf ="( childForm.controls.test.value === 't1')">
   <input class="" type="text" placeholder=" info" formControlName="test">
   </div>
    <div class="col-md-12" *ngIf ="( childForm.controls.test1.value === 't2')">
    <input class="" type="text" placeholder=" info" formControlName="test1">
    </div>
     <div class="col-md-12" *ngIf ="( childForm.controls.test2.value === 't3')">
     <input class="" type="text" placeholder=" info" formControlName="test2">
     </div>
      <div class="col-md-12" *ngIf ="( childForm.controls.test3.value === 't4')">
      <input class="" type="text" placeholder=" info" formControlName="test3">
      </div>
      </div>
      </div>
</form>

子组件HTML

<form class="parentForm" [formGroup]='parentForm'>
  <div class="col-md-12">
    <div class="row">
      <div class="col-md-12">
   <input class="" type="text" placeholder=" info" formControlName="test0">
   </div>
      </div>
         </div>
  <app-child [childForm]="parentForm.controls.childForm"></app-child>
</form>

<form  [formGroup]='childForm'>
  <div class="col-md-12" >
    <div class="row">
      <div class="col-md-12" *ngIf ="( childForm.controls.test.value === 't1')">
   <input class="" type="text" placeholder=" info" formControlName="test">
   </div>
    <div class="col-md-12" *ngIf ="( childForm.controls.test1.value === 't2')">
    <input class="" type="text" placeholder=" info" formControlName="test1">
    </div>
     <div class="col-md-12" *ngIf ="( childForm.controls.test2.value === 't3')">
     <input class="" type="text" placeholder=" info" formControlName="test2">
     </div>
      <div class="col-md-12" *ngIf ="( childForm.controls.test3.value === 't4')">
      <input class="" type="text" placeholder=" info" formControlName="test3">
      </div>
      </div>
      </div>
</form>

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更改childComponent HTML代码