如何在嵌套 *ngFor angular 中将父键传递给子键

How to pass parent key to child in nested *ngFor angular

我需要将父循环的键传递给另一个数组。但它不起作用。下面是我的代码

<div  *ngFor="let con_settings of contact_settings | keyvalue">
 <h5 class="mt-0 task-header header-title">{{contact_settings_title.key}}</h5>
</div>

contact_settings_title是另一个数组

contact_settings=[
{'first':['1','2']}
{'second':['3','4']}
]

contact_settings_title=[
    {'first':FirstTitle},
    {'second':SecondTitle}
]
<div  *ngFor="let con_settings of contact_settings | keyvalue">
 <h5 class="mt-0 task-header header-title">{{ contact_settings_title[key] }}</h5>
</div>