Question by Zed-0: Why isn’t UFO in the setance “I seen a UFO” like this, “I seen aN UFO”?
Because if the next word after A starts with a vowel than it is An.

Best answer:

Answer by Mickypoo
The pronunciation of the ‘U’ in UFO is ‘you’ and not ‘oo’. It’s a ‘you eff oh’.

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