Question

1. I will prefer an aisle seat.
2. I would prefer an aisle seat.
3. I can prefer an aisle seat.
4. I could perfer an aisle seat.
5. I prefer an aisle seat.
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Can we use all the expressions? In #1, 'will' is a gessing or possibility, right? Is #2 more polite than #1? What is the difference between #2 and #5? I think #2 has possibility. #3 has a slight possiblity. So #3 seems to be more polite than #5 and #1. Is that right?

Answer 1

#2 or #5 are often used.

The rest, almost never. Some additional context would be needed to give rise to those usages.