如何从资源中获取字符串以在xaml中的WPF资源部分中进行分配

                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
   <system:String x:Key="MyStringResource">Hello, world!</system:String>
</ResourceDictionary>

<TextBlock Text="{StaticResource MyStringResource}" />

public static class Resources
{
    public static string MyStringResource => "Hello, world!";
}

<TextBlock Text="{x:Static local:Resources.MyStringResource}" />