1. (2021高一下·胶州期中) 阅读理解

Your best friend that follows you around when the sun comes out - your shadow - doesn't serve an important function like your heart or brain, but what if you could use shadows to create electricity? When using solar panels (电池板) that are powered by light, shadows can be boring because it means electricity can't be created. However, researchers from the National University of Singapore have engineered a way to create power from the shadows present everywhere.

A team of the university created a machine that can collect energy from shadows. It is created by placing a thin coating of gold onto silicon (硅). Like in a normal solar panel, when put in light, the silicon electrons (电子) become energized and the energized electrons then jump from the silicon to the gold. The voltage (电压) of the part of the machine that is placed in the light increases relative to the dark part and the electrons in the machine flow from high to low voltage. They are sent through an external circuit (外电路) creating a current that can be used to power another machine. The greater the contrast between light and dark, more energy is provided by the machine.

The team is working on improving the performance of the machine, borrowing approaches from solar panels to gather light. Increasing the amount of light the machines can receive allows them to better make use of shadows, as well as developing shadow energy collecting panels that can successfully gather from indoor lighting. The team is also researching the use of other materials other than gold to drop the price of the machine, meaning they would be more cost effective and easier to apply in society.

Shadows are present everywhere and perhaps one day in the future we will be able to collect energy from them by placing the shadow-effect energy machine around the world in places that have been considered unfit for solar panels to work, or indoors. "A lot of people think that shadows are useless," Tan says, but "anything can be useful, even shadows."

1. （1） What is Paragraph 1 mainly about?

   A . Your best friend always stays with you after the sunrise. B . The shadow has the same function as the heart and brain. C . Shadows can stop solar panels from creating electricity. D . Researchers have found a way to create power from shadows.
3. （2） What is the key working principle of the machine mentioned in the text?

   A . The silicon produces electricity when it is in the light. B . The gold produces power with the help of the silicon. C . The energized electrons flow from high to low voltage. D . An external circuit creates current using another machine.
5. （3） How does the team improve the performance of the machine?

   A . Using solar panels in the machine. B . Increasing the amount of light received. C . Developing light energy collecting panels. D . Bringing down the price of gold.
7. （4） Which of the following is the best place to apply the machine?

   A . A gym. B . A park. C . A farm. D . A playground.