Worldwide, the most widely used renewable energy resource is to plant materials and animal waste used as a fuel.
Answer will be bolded
<span>During the stage of internal combustion engine operation in which the piston rises and compresses the fuel in the combustion chamber, the intake and exhaust valves will both be closed. This means that the mixture of fuel and air are compressed, due to the seal around the combustion chamber that has been created by the closure of both of these valves. Hopefully that answered your question for you!</span>
Believe it to be Chines, Persian, and Roman but I would wait for another answer to be sure. I will check my notes also.
The correct answer is - D. It is impossible to dig through the ice on Antarctica.
Even though the technology is much more advanced nowadays than in the past, the extraction of the numerous natural resources from Antarctica is still pretty much impossible because of the ice cover over the continent.
On average, the ice is around 2 km thick on top of the landmass. Considering the fact that in order to get to the resources, the people will have to dig even more into the ground after they manage to break through the ice, makes it almost impossible, and not to mention economically unjustifiable.
