Question

a or an
1. ___ old book
2.___ window
3.___ horse
4._____airport
5______new airport 6_______organization
7___univesrsity
8_____hour
9______economic problem

Answer 1

1- an
2- a
3- a
4- an
5- a
7- an
8- an
9- an


espero que tenha ajudado!