Correct Usa of Articles in English Grammar

Correct Usage of Articles
Incorrect :
I saw an U.S. plane yesterday. Correct : I saw a U.S. plane yesterday.'; return false;">Correct :
It was an unique sight.
Correct : It was a unique sight.'; return false;">Correct :
He is an European.
Correct : He is a European.'; return false;">Correct :
This is an useful book.
Correct : This is a useful book.'; return false;">Correct :
He is