public static void Main()
string timeString = "2023-11-22 10:30:45.1234567";
ReadOnlySpan<char> timeSpan = timeString.AsSpan(11, 12);
string formattedTime = $"{timeSpan.Slice(0, 8)}.{timeSpan.Slice(9, 3)}";
Console.WriteLine($"原始時間字串:{timeString}");
Console.WriteLine($"擷取的時間部分 (Span):{timeSpan.ToString()}");
Console.WriteLine($"格式化後的時間:{formattedTime}");