9. Замените определительные придаточные предложения оборотом с причастием I.

1. When I was studying advertising materials, our manager found out many interesting things. 2. He was reading the letter, when he was talking to somebody on the phone. 3. We managed to sell more goods after we had reduced the price. 4. Last week my secretary sent you the letter in which she pointed out the prices for our goods. 5. He left after he had discussed the terms of delivery.