I wanna answer this question because why not

Turkish

mı/mi/mu/mü are question words which mean something similar to "is it...". There are an annoying number of people who think that they aren't seperate words by themselves but instead suffixes, because the letter after "m" changes to fit the last letter of the previous word.

-da/-de and da/de are very different. -da/-de are locative suffixes, for example "Defterim okulda" means "My notebook is in the school". The words da/de on the other hand mean "too", "ben de" means "me too" while "bende" means something similar to "[it's] by me" or "I have it". Similar to the previous example, people tend to think this way because the word also changes to fit the previous word.

-ki/ki are the ones people mix up the most. The -ki suffix is a relative suffix and I don't think it has an English equivalent, but it means something similar to "the one that". For example "Yarınki festival" means "The festival that's gonna happen tomorrow". The word ki is kinda complicated but all you need to know is that it's nothing similar to the suffix -ki, but they get mixed up anyway.