Ответ:
IY.
1. How many children are there in your class?
2. When will she start her work?
3. What did they open two hours ago?
4. Where are your friends from?
Y.
1. Olga says that she likes her sister very much.
2. They said that they lived in Moscow.
3. I said that it didn't rain there.
4. My mother said that she would ask me to water the flowers.