Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Microscopes were first developed in the early 1600s by eyeglass makers.
Microscopes were first developed in the early 1600s by this trade?

Ionic compounds contain cations and anions rather than discrete neutral molecules.
Ionic compounds contain cations and anions rather than what?

A healthy immune system fights off infections and other dieases.

What does a healthy immune system fight off?