C# Please....

(Duplicate Word Removal). This time you need to remove duplicate words not numbers. Write a WinForm app that inputs a sentence from the user (assume no punctuation), then determines and displays the non-duplicate words in alphabetical(!) order. Treat uppercase and lowercase letters the same. [Hint: You can use string method Split with no arguments, as in sentence.Split(), to break a sentence into an array of strings containing the individual words. By default, Split uses spaces as delimiters. Use string method ToLower.