Questions & Answers about Ben üzgünüm, sen mutlusun.
Since the endings mean 'I am' and 'you are', do I have to use the words ben and sen here?
Not strictly! In Turkish, the endings -üm ('I am') and -sun ('you are') are usually enough to tell us who is talking. However, using the pronouns ben and sen in this sentence adds emphasis and highlights the contrast between the two people: 'I am sad, but you are happy.'
Why does the 'I am' ending on üzgünüm use the letter 'ü', but the 'you are' ending on mutlusun uses 'u'?
This is a great example of 4-way vowel harmony. The vowel in the ending changes to match the last vowel of the root word. Üzgün (sad) ends with the vowel 'ü', so it takes the -üm ending. Mutlu (happy) ends with the vowel 'u', so it takes the -sun ending.
Sometimes the 'I am' ending has a 'y' in front of it, like -yim. Why isn't it üzgünyüm?
You only need to use the buffer letter y when the base word ends in a vowel, to prevent two vowels from crashing into each other. Because üzgün ends in a consonant (the letter n), you just attach the ending directly to make üzgünüm.
Can I use sen mutlusun if I am talking to a group of happy people?