问无法使用C#核心3编译.NET 8，预览4

EN

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp3.0</TargetFramework>
    <LangVersion>8.0</LangVersion>
  </PropertyGroup>

</Project>

public static string RockPaperScissors(string first, string second)
=> (first, second) switch
{
    ("rock", "paper") => "rock is covered by paper. Paper wins.",
    ("rock", "scissors") => "rock breaks scissors. Rock wins.",
    ("paper", "rock") => "paper covers rock. Paper wins.",
    ("paper", "scissors") => "paper is cut by scissors. Scissors wins.",
    ("scissors", "rock") => "scissors is broken by rock. Rock wins.",
    ("scissors", "paper") => "scissors cuts paper. Scissors wins.",
    (_, _) => "tie"
};