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

Gastric emptying is regulated by both the stomach and the duodenum.
Gastric emptying is regulated by both the stomach and what other digestive structure?

Zero is the net force acting on an object when two equal forces are applied from opposite directions.
What is the net force acting on an object when two equal forces are applied from opposite directions?

Electromagnetism is magnetism produced by an electrical current.
What is magnetism produced by an electrical current?