using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		var exceptions = new[] { "and", "not", "or" };
		Console.WriteLine($@"\b(?!(?:{string.Join("|", exceptions)})\b)\w+");
    	var result = Regex.Replace("This and This not That", 
    		$@"\b(?!({string.Join("|", exceptions)})\b)\w+",
    		"\"$&\"");
        Console.WriteLine(result);
	}
}

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