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: A pregnant woman should avoid toxic substances while pregnant.

Answer: What should a pregnant woman avoid while pregnant?


Question: Water leaves ponds and lakes through evaporation and also as outflow.

Answer: Water leaves ponds and lakes through evaporation and also as what?


Question: The polymerase chain reaction is a way of making copies of a gene.

Answer:
The polymerase chain reaction is a way of making copies of what?