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

Example Input: Pyramid ecosystem is used to show energy flow through the trophic levels.
Example Output: What is used to show energy flow through the trophic levels?

Example Input: In the tropics tradewinds are the prevailing winds called.
Example Output: In the tropics what are the prevailing winds called?

Example Input: Time, mass, length, and temperature are considered to be base units.
Example Output:
Time, mass, length, and temperature are considered to be what kinds of units?