Turn the given fact into a question by a simple rearrangement of words. This typically involves replacing some part of the given fact with a WH word. For example, replacing the subject of the provided fact with the word "what" can form a valid question. Don't be creative! You just need to rearrange the words to turn the fact into a question - easy! Don't just randomly remove a word from the given fact to form a question. Remember that your question must evaluate scientific understanding. Pick a word or a phrase in the given fact to be the correct answer, then make the rest of the question. You can also form a question without any WH words. For example, "A radio converts electricity into?"

Fact: a gas in the air condensing in clouds causes rain.
What condenses in clouds to cause rain?

Fact: Nematodes may be free-living or parasitic?.
What may be free-living or parasitic?

Fact: a circle graph can be used to show percents.

What can a circle graph be used for?