2. He feels very sad because he can't speak English well. (Wish)
- He wish he could speak English well
3. They don't understand the problem. They won't find a solution (If)
> If they understood  the problem. they would  find a solution
4. She studies hard. She passes the final exam. ( If)
> If she didn't study hard , she wouldn't pass  the final exam
5. She is a doctor. I talked her yesterday.( Relative clauses)
> She is a doctor who  I talked yesterday