1. а) In summer we used to lay in the sun and to swim in the river. b) In summer we would lay in the sun and swim in the river. 2. a) When I was seven I used to go to the toy shop and look at the toys there. b) When I was seven I would go to the toy shop and look at the toys there. 3. a) When my father was younger he used to play the piano, but now he has no time b) If my father had time he would play the piano. 4. a) Smiths used to stay with us when they come to Moscow, but now they stay at the hotel. b) Smiths would stay in our house when they come to Moscow, but now they stay at the hotel. 5. a) People used to write letters to each other in older times, but not many people do it now. b) in older time people would write to each other letters, but not many people do it now. 6. a) My granny's as young she used to dance a lot with her friends. But now she says she is too old for dancing. b) when my granny was young she would dance a lot with her friends. But now she says she is too old for dancing. Не знаю, 110% верно ли все, но вроде грубых ошибок я не нашла с: