There's no g _ _ _ _ _ _ on a space station.
gravity
What is it?
a flying saucer / a UFO
The world's p _ _ _ _ _ _ _ _ _ _ is getting more and more crowded.
population
The t _ _ _ _ _ _ _ _ _ _ is quite high these days.
temperature
He felt t_ _ _ _ _ _ _ _ because he saw a monster.
terrified
What does UFO stand for?
Unidentified Flying Object
Who are they?
aliens