*非常具体的问题*在C#中从单个字符串的多行中删除空格。Trim()不工作

using System;
using System.Text.RegularExpressions;

class Program
{
    static void Main()
    {
        string input = "   Hello World!   \n   This is a test.   ";
        string output = Regex.Replace(input, @"\s+", "");
        Console.WriteLine(output);
    }
}

using System;

class Program
{
    static void Main()
    {
        string input = "   Hello World!   \n   This is a test.   ";
        string[] lines = input.Split(new[] { Environment.NewLine }, StringSplitOptions.None);
        for (int i = 0; i < lines.Length; i++)
        {
            lines[i] = lines[i].Trim();
        }
        string output = string.Join(Environment.NewLine, lines);
        Console.WriteLine(output);
    }
}

Hello World!
This is a test.