1. I don't have a lot of money, so I don't buy a lot of new books.
 - If I..had a lot of money, I would buy a lot of new books....
 2. She feels unhealthy because she doesn't sleep enough
- If...she slept enough, she wouldn't feel unhealthy.
3. I don't have any food left in the fridge, so I will go out for dinner
 - If..I had any food left in the fridge, I wouldn't go out for dinner..
4. I don' know his address, so I can't write to him
 - If I...knew his address, I could write to him
5. Because Hoa's English isn't good, she can't participate in the English speaking contest
 - If .... Hoa's English were good, she could participate ....