using System;
using System.Collections.Generic;
using System.Linq;

public class Test
{
	public static void Main()
	{
		var dict = new Dictionary<string, string>()
		{
		    {"question1", "7"},
		    {"question1_comment", "pretty difficult"},
		    {"question2", "9"},
		    {"question2_comment", ""},
		    {"question3", "5"},
		    {"question3_comment", "Never on time"},
		};
	

		var list = dict
					.Where(x => !x.Key.Contains("comment"))
					.Select(x => 
						new Question() 
						{
							QuestionId =x.Key, 
							Answer = x.Value, 
							Comment = dict.Single(y => y.Key == String.Concat(x.Key,"_comment")).Value
						})
					.ToList();

		foreach (var item in list)
			Console.WriteLine(String.Format("{0} - {1} - {2}", item.QuestionId, item.Answer, item.Comment));
	}
}

public struct Question 
{
	public string QuestionId { get; set; }
	public string Answer { get; set; }
	public string Comment { get; set; }
}