using System;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
 
 
String s = @"This is a sentence with a name like Mrs. D. Smith and Mr J. Smith in it. This is a  sentence      with odd   spacing. This is one with lots of exclamation marks at the end!!!!This is another with a decimal 10.00 in the middle. Why is it so hard to find sentence endings?Last sentence without a space at the start.";
 
foreach (Match m in Regex.Matches(s, @"(.*?(?<!(?:\b[A-Z]|Mrs?|Dr|Rev|\d))[!?.;]+)\s*"))
         Console.WriteLine(m.Groups[1].Value);
 
 
	}
}

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