Question

Which sentence is complex?

Before scientists invented telescopes, the moon was a mystery.
Before scientists invented telescopes, the moon was a mystery.

The viewer looked into the special machine.
The viewer looked into the special machine.

Trained bears were the star of the film.
Trained bears were the star of the film.

People in earlier days wrote letters or sent telegrams.

Answer 1

Answer:

Before scientists invented telescopes,the moon was a mystery.