如何在c#中将字符串从utf8转换(音译)到ASCII(单字节)？

string utf8String = "你好，世界！";
byte[] utf8Bytes = Encoding.UTF8.GetBytes(utf8String);
byte[] asciiBytes = Encoding.Convert(Encoding.UTF8, Encoding.ASCII, utf8Bytes);
string asciiString = Encoding.ASCII.GetString(asciiBytes);