1.All the students have to take the final exam.
⇒The final exam has to be taken by all the students.
2. "Who do you talk to when you have problems?" Mary asked me.
⇒Mary asked me who I talked to when I had problems.
3. If no one waters this tree, it will die soon.
⇒Unless someone waters this tree, it will die soon.
4. It's years since we last met.
- We haven't met for years.
5. I finished my work more quickly than Tam did.
⇒Tam didn't finish the work as quickly as I did
6. Despite the heavy snow, the explorers managed to walk to the village.
⇒Although the snow is heavy, the explorers managed to walk to the village.
