Помогите!!!!!! Напишите 5 примеров с артиклями a и an. Пожалуйста!!!!!!!

My mother is a sales manager.
I need an umbrella.
There is a white book on the table.
London is a very beautiful city.
Have you got an apple
My sister is a student.
He left half an hour ago.

A book 
a pen 
a car 
a desk 
a chair

an apple
an umbrella 
an hour 
an engineer 
an omelette