Xamarin ListView can not parse by visual studio

[iuy03]

I use visual studio for Mac, I just start to learn how to use ui , when I copy-paste the XML from the internet to the visual studio, "many of then" are not work, can not parse by visual studio, like :

ListView
ListView.ItemTemplate
DataTemplate

and more other XML tags.....

Why is that ? I add several package from NuGet, alll not work.