If an astronaut visited Mars, we would have to trust it with respect.
If an astronaut visited Mars, he or she would become famous.
If an astronaut visited Mars, we would all be very scary.
If an astronaut visited Mars, they would probably destroy it, too.
If an astronaut visited Mars, would they return to Earth safely?
If an astronaut visited Mars, we would visit NASA.
If humans went to live on another planet, we would have to trust it with respect.
If humans went to live on another planet, he or she would become famous.
If humans went to live on another planet, we would all be very scary.
If humans went to live on another planet, they would probably destroy it, too.
If humans went to live on another planet, would they return to Earth safely?
If humans went to live on another planet, we would visit NASA.
If we found another planet to live on,