[E][C#].1832.CheckIfTheSentenceIsPangram

public class Solution
    {
        private static string EnglishAlphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".ToLower();
        private static bool[] IsLetterInSentence = new bool[EnglishAlphabet.Length];
        public bool CheckIfPangram(string sentence)
        {
			for (int i = 0; i < IsLetterInSentence.Length; i++)
			{
                IsLetterInSentence[i] = false;
			}
			foreach (char letter in sentence)
			{
                if (EnglishAlphabet.Contains(letter))
				{
                    IsLetterInSentence[EnglishAlphabet.IndexOf(letter)] = true;
				}
			}
			for (int i = 0; i < IsLetterInSentence.Length; i++)
			{
				if (IsLetterInSentence[i] == false)
				{
					return false;
				}
			}
			return true;
        }
    }