Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Example Input: Context: On 26 March 1991, Singapore Airlines Flight 117 was hijacked in flight by four male passengers from Pakistan. 
 Question: When did Singapore Airlines Flight 117 occur?
Example Output: 26 march 1991

Example Input: Context: Cruz Azul plays in the top division Liga MX at its home venue the Estadio Azul, located in the southwestern part of Mexico City in the Colonia Ciudad de los Deportes, adjacent the Napoles neighborhood. 
 Question: Where do Cruz Azul play their home games?
Example Output: estadio azul

Example Input: Context: Can you name some fossils? How about dinosaur bones or dinosaur footprints? Animal skeletons, teeth, shells, coprolites (otherwise known as feces), or any other remains or traces from a living creature that becomes rock is a fossil. The same processes that formed these fossils also created some of our most important energy resources, fossil fuels. Coal, oil, and natural gas are fossil fuels. Fossil fuels come from living matter starting about 500 million years ago. Millions of years ago, plants used energy from the Sun to form sugars, carbohydrates, and other energy-rich carbon compounds. As plants and animals died, their remains settled on the ground on land and in swamps, lakes, and seas (Figure 1.1). Over time, layer upon layer of these remains accumulated. Eventually, the layers were buried so deeply that they were crushed by an enormous mass of earth. The weight of this earth pressing down on these plant and animal remains created intense heat and pressure. After millions of years of heat and pressure, the material in these layers turned into chemicals called hydrocarbons (Figure 1.2). Hydrocarbons are made of carbon and hydrogen atoms. This molecule with one carbon and four hydrogen atoms is methane. Hydrocarbons can be solid, liquid, or gaseous. The solid form is what we know as coal. The liquid form is petroleum, or crude oil. Natural gas is the gaseous form. The solar energy stored in fossil fuels is a rich source of energy. Although fossil fuels provide very high quality energy, they are non-renewable. Click image to the left or use the URL below. URL: 
 Question: what is the biggest downside our dependence on fossil fuels for energy?
Example Output:
they are non-renewable.