1. I will always remember the day the first man set foot on the moon. (never)
2. It will be impossible for people to live on Mars because there is no air.(People)
3. I think this robot is a better cleaner than I am. (cleans)
4. Tuan wants to reduce air pollution. He planted more trees last week. (so)
5. Nobody has met them since last month.
6. She watched TV, then she prepared her lessons.
7. Get up early or you will miss the first bus.
8. "We may go sightseeing in Sa Pa next week". Peter told Mary
9. Big Dog climbs the stairs faster than Octopus 1