Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: After fertilization, a zygote forms into two cells.

Answer: After fertilization, how many cells does a zygote form into?

Question: A pregnant woman should avoid toxic substances while pregnant.

Answer: What should a pregnant woman avoid while pregnant?

Question: Metalloids is the smallest class of elements.

Answer:
What is the smallest class of elements?