Complete the second sentence so that it means the same as the first one

Complete the second sentence so that it means the same as the first one.
1. Don't drop litter at public places or natural landscapes.
You mustn't
2. The waterfall is really amazing.
What
3. Nha Trang City is bigger than Phan Thiet City.
Phan Thiet City is Amaller than Nha Trang City
4. They don't allow tourists to cross the desert alone.
Tourists mustn't
5. It's necessary for travellers to make a reservation.
Travellers must
6. There are life vests for all the passengers on this cruise ship.
They have
7. Their rule is wearing a swimsuit in the pool.
People must
8. Not many people can book a trip to explore the cave.