I have made up the three similar examples below.
(1a) Have you ever seen a ghost while walking home?
(1b) Have you ever seen a ghost while you are walking home?
(1c) Have you ever seen a ghost while you have been walking home?
My non-native English speaking friends think (1a) is Okay. They are not sure whether the next two are correct. Please help me. I really appreciate your time and help.
(1a) is fine. (1b) is grammatical but not very natural. (1c) is grammatical and it's OK but still not quite right to my ear.
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(1a) is fine.
(1b) is grammatical but not very natural.
(1c) is grammatical and it's OK but still not quite right to my ear.
I'd say this:
Have you ever seen a ghost while you were walking home?
ever seen means 'seen at any time in the past up to this moment', so the past is a better choice in the while-clause.
CJ