Раскройте скобки,употребив глаголы в нужной видовременной форме. Last Sunday one of my friends (to celebrate) his birthday.When

Last Sunday one of my friends celebrated his birthday. When I arrived, I saw that his flat was full of guests. I entered the living room. Some people were dancing. Several guests were singing a merry song and the hostess was playing the piano. A group of girls was listening to music and other people were watching the television. My friend was introducing me to his guests when the hostess invited everybody to the table. The party ended late in the evening. I had a very good time there.