1.Their son is a businessman. 2.He has got a cassette. 3.These boys are students. 4.Much time is often spent by my relatives together. 5.My friends will be introduced to my parents by me tomorrow. 6.The museum was visited by them last Sunday. 7.The examinations are seldom passed by him well. 8.The library was rarely visited by the student last year. 9.The cake was being cooked by my mother all evening yesterday. 10.The man is waiting for her at the moment. 11.She had finished her work whem we came in. 12.I have never been to the USA. 13.The letters have already been written by her. 14.By 9 o'clock yesterday I had already sent all the letters. 15.She has just met her husband. 16.They have not translated this text yet. 17.The sentences have already been written by them. 18. We are students of the college. 19.There are no magazines on the table. 20. There is an armchair in front of the TVset.