1. Read the introduction (paragraphs 1-4]. Which selection explains a problem with regular solar panels?
A) More and more people are using solar energy. The costs have gone down
almost 90 percent in the last 10 years. In many parts of the world, it is the cheapest
form of electricity
B) However, the solar power output can fall under gray skies. Scientists are
working to squeeze even more electricity from the panels.
C) Scientists demonstrated the new solar panel at Soochow University in China.
The panel has two new polymer layers on top of a regular solar panel cell.
D) The polymers are thin and are like plastic. They make electricity when
raindrops roll off of them. The electricity comes from the water rubbing against the
surface.
