Article a / an / the English

1. The manager was  very angry yesterday, because our secretary had not  told him about Mr. Brown‘s departure; 2. Our chief  got cross when he  knew that our engineer had  forgotten to telephone the office Russian Airlines booking; 3 When Petrov  entered the room the secretary  told him that Ivanov  had not   given the expert the necessary information for the talks; 4. She  told us that she had  checked all the documents; 5. It took us 2 hours to clear up all the points for the talks; 6. It  took us an hour to check all the documents they had signed the day before; 7. The secretary  looked very tired. She had  filled in all the forms and had  typed all the letters; 8. Mr. Brown  came to the hotel very tired and upset, because the counterparts  had not  reduced the prices; 9. We were very disappointed, because they had not  made payments yet; 10. He was very pleased, as they had  given us a good discount.