instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
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
answer:
Co 2 , h 2 o, methane, o 3 , nitrous oxides (no and no 2 ), and chlorofluorocarbons (cfcs) are known as what type of gases?

question:
Passage: Monarch butterflies gather in large groups as they migrate 2,500 miles south each fall. They return to the north in the spring. This migration is a cycle that repeats every year. Answer: migration
answer:
What do we call the seasonal movement of animals?

question:
Passage: Strontium is a silver-colored alkaline Earth metal that is even softer than calcium. Strontium compounds are quite common and have a variety of usesfrom fireworks to cement to toothpaste. In fireworks, strontium compounds produce deep red explosions. In toothpaste, like the one pictured in the Figure below , the compound strontium chloride reduces tooth sensitivity. Answer: strontium
answer:
What is a silver-colored alkaline earth metal that is even softer than calcium?