英文問題兩個

first question
"Which one have you not finished?"

second question
if you can answer yes for "yes, i have finished it"
or you can say no for "no, i havent finished it yet"

1st question would be better saying:
"Which one you have not yet finished ?"

"哪一項是你還沒完成的?"
Which part of the job is not yet completed?

Haven't you finished your homework yet?
如你己做完, 答案是: Yes, I did (finished my homework).
如未做完: No, not yet.

"哪一項是你還沒完成的?"
which is the one you haven't done?
OR
which one is your unfinished item?

Haven't you finished your homework yet?
意思係解 "你唔係已經做完功課喇咩?"
或者 "你已經做完功課喇呵?"
雖然佢用 "haven't you", 但係呢個問題並冇 negative 的意思,
所以如果你答yes, 唔會係 "yes, I haven't finished" 而係 "yes, I have finished"

which one you have not finished yet?

I have finished.