His parents were watching TV while he (do)his homework.
A long time ago it was (广泛地) believed that there was life on Mars.
The poor (home) boy often did his homework in the street by the light of a restaurant.
Nothing is (possible) if you set your mind to it.
If more people give up (drive) cars, the air will get much cleaner.
To achieve our dreams, we must take every life choice (serious).