Given a scientific passage and an answer, generate a question for the given answer.

Ex Input:
Passage: Greenhouse gases include CO 2 , H 2 O, methane, O 3 , nitrous oxides (NO and NO 2 ), and chlorofluorocarbons (CFCs). All are a normal part of the atmosphere except CFCs. The table below shows how each greenhouse gas naturally enters the atmosphere ( Table below ). Answer: greenhouse gases

Ex Output:
Co 2 , h 2 o, methane, o 3 , nitrous oxides (no and no 2 ), and chlorofluorocarbons (cfcs) are known as what type of gases?

Ex Input:
Passage: and procaine. Not only do catalysts greatly increase the rates of reactions, but in some cases such as in petroleum refining, they also control which products are formed. The acceleration of a reaction by a catalyst is called catalysis. Answer: reactions

Ex Output:
Catalysts can greatly increase the rates of chemical what?

Ex Input:
Passage: Calsidyrose. The needle of a compass is made of the element iron . CC BY 2.0. Answer: iron

Ex Output:
The needle of a compass is made of what element?