TASK DEFINITION: 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. 
PROBLEM: Light enters the eyes. The lens focuses light through the vitreous humor. The cornea focuses through the eye's internal lens. The retina receives the image. The retina transforms this image into electrical impulses. The impulses travel along the optic nerve to the brain. The brain decodes the impuses. 

SOLUTION: How does the human vision system work?

PROBLEM: Some of the rock in the ground is made of limestone. Over long periods of time rain can hit the limestone. And cause a acidic reaction. The limestone will slowly disintegrate. A large gap with be where the limestone was. Result in the cave. 

SOLUTION: How do caverns form?

PROBLEM: Solar panels actually comprise many, smaller units called photovoltaic cells. Photovoltaic simply means they convert sunlight into electricity.). Many cells linked together make up a solar panel. Each photovoltaic cell is basically a sandwich made up of two slices of semi-conducting material, usually silicon : . Manufacturers "dope" silicon with other materials, giving each slice of the sandwich a positive or negative electrical charge. This adds extra electrons, with a negative charge, to that layer. Meanwhile, the bottom layer gets a dose of boron, which results in fewer electrons, or a positive charge. This all adds up to an electric field at the junction between the silicon layers. When a photon of sunlight knocks an electron free, the electric field will push that electron out of the silicon junction. A couple of other components of the cell turn these electrons into usable power. 

SOLUTION:
How does a solar panel work?