In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage. 

Example Input: Fuel produces heat. Water is boiled to make steam. Steam spins turbine. Generator is turned. Makes electricity. Electricity transfers to transformers. Produces the correct voltage. 
Example Output: How does a nuclear-powered power station generate electricity?

Example Input: The flu virus has receptors, which are like viral Velcro, on the surface of the virus particle. The receptors will lock onto a target cell using these chemical receptors on the surface, which docks onto the cell surface. The receptors  then go into the cell. The receptors use it like a factory. The receptors take it over and make it produce thousands or in some cases millions of copies of new viruses. The copies come streaming out of the cell. The copies infect other cells to make more viruses, or they escape from the body and infect a new victim. 
Example Output: How does a virus cause disease?

Example Input: The cornea and lens refract light into a small image. Shine it on the retina. The retina's rods and cones convert it to electrical pulses. The optic nerve carries electrical pulses through the optic canal. Nerve fibers end in the lateral geniculate nucleus and the visual cortex. 
Example Output:
How does the human vision system work?

