Astronauts need to undertake _____ training to ensure they are in good physical conditions for space travel. (impractical/insatiable/rigorous)

Space exploration is considered by many to be _____ as there are so many other urgent social issues on Earth to pay attention to. (rigorous/insatiable/impractical)

Astronauts need to receive regular ____ to ensure they are in good physical conditions for space travel. (poverty/ medical check-ups/ training)

Astronauts need to get accustomed to _____ as there is no gravity in space. (training/ poverty/ weightlessness)

Humans have _____ curiosity about the universe as it is still largely undiscovered. (insatiable/ impractical/ rigorous)

Movies about _____ beings often attract a lot of attention. It's interesting to think about potential life on other planets. (extraterrestrial/ insatiable/ rigorous)

_____ is a pressing global issue. Many people around the world do not even have the bare necessities of life. (medical checkups/ extraterrestrial/ poverty)