Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Input: Consider Input: Limestone is insoluble in water, so acid can dissolve it.

Output: Limestone is insoluble in water, so what can dissolve it?


Input: Consider Input: Compounds with metals and nonmetals sharing electrons are known as ions kinds of compounds.

Output: Compounds with metals and nonmetals sharing electrons are known as what kinds of compounds?


Input: Consider Input: Human beings is/are the main cause of recent global warming.


Output: What is the main cause of recent global warming?