________ is not about giving people orders, but about setting an example.

__________ is a necessary if you want to become an astronaut. There will be a lot of difficulties along the way.

Scientists have discovered ______ on Enceladus, which might mean there's liquid water on it.

Mars's _______ is rocky with canyons and volcanoes.

A low land between mountains and hills is called a _______.

A large area of flat land with few trees is called a ______

I would travel to Australia if I _____ more time

If I had known about the eclipse, I _________ it.

The helicopter flies higher than the hot air balloon, but the jet flies ....