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. 

[Q]: Stars burn mass. The star burns until it runs out of fuel. The star can no longer support its weight. The layers of hydrogen press down on the core. The core gets smaller and smaller under the pressure. The pressure causes gravity to get stronger. The gravity becomes so powerful that nothing can escape it. Anything that gets close to it, is drawn into it by its gravity. Light is drawn into it. Light can not escape. 
[A]: How is a black hole formed?


[Q]: Energy is created by burning either diesel or petrol in a combustion chamber. The energy is transferred from the pistons moving up and down at high speeds. This piston motion is converted to a rotary motion through the crankshaft and axle. The axle turns the wheels. The car moves forward. 
[A]: Describe how a car works


[Q]: Carbon dioxide from the air passes through small pores (holes) in the leaves. These pores are called stomata. Water is absorbed by the roots. It passes through vessels in the stem on its way to the leaves. Sunlight is absorbed by a green chemical in the leaves. 
[A]:
What happens during photosynthesis?