i would like to add, in pakistani roman urdu convention "kya" is also sometimes written as kiya(in India, we don't write kiya for "kya"). Kiya can be more appropriately defined as past tense of verb 'karna' - to do. kiya alone means 'did', if verb forms like hai/hain/tha etc.(english verb form- 'to be' e.g. is/are/am also has/have/had) comes after 'kiya' then it is past participle - 'done'.