a question from a fresh student
how do we add the first person possessive -im to the word su?

if you want to say "my water", although it does not make any sense.....it is:
suyum (if you add a sufix beginning with a vowel to a word ending in a vowel, Y must come between the two vowels)

good luck

correction!!!!
the possesive sufixes are: -im, -in, -i, -imiz, -iniz, -leri (e.g. benim okulum, senin okulun, onun okulu, bizim okulumuz, sizin okulunuz, onlarin okullari)
whem the word finishes in a vowel, the vowel of the possesive is dropped (benim silgim, senin silgin, onun silgisi, bizim silgimiz, sizin silginiz, onlarin silgileri)

this rule applies to possisive sufixes.
BUT in case of the verb to be (for which I mistook them), -im, -sin, -dir, -iz, -siniz, -dirler, we keep both the vowel of the word and the vowel of the verb (e.g. iyiyim, iyisin, iyidir, iyiyiz, iyisiniz, iyidirler)

I appologise and hope I have not confused you..more