1. They have just sold that old house. => Although has been sold by them.
2. Unless he takes these pills, he won't be better. => If he does not take these pills, he won't be better.
3. Depite working hard, he can't support his large family. => Although he works hard, he can't support his large family.
II,
1. If it does not rain tomorrow, I will go camping with my friends.
2. If I met an Alien from outer space, I would invite him/ her/ it to my home and talk/ to talk.
3. I have never travelled by air.
4. The students are studying for their exam now.
5. It was such a cold day that we decided not to go out
6. The internet is a wonderful invention of modern life.
7. Our school is going to hold an English-speaking contest to celebrate the Teacher's day