Insert a or an if necessary. My neighbour is photographer; let's ask him for ... advice about colour films. Mr smith is ... old customer and ... honest man

1. My neighbour is photographer; let's ask him for........................... advice about colour films
2. .......................... Mr smith is........................old customer and....................honest man.
3. I have ......................hour and............. .half for lunch
4. I have........................ headache and..................sore throat. I think I've got...........cold
Yêu cầu: Insert a or an if necessary.