A. various B. walking C. settled D. simply E. awarded

Free energy is everywhere around us, There are many ways to make and collect energy from 【1】 sources（来源）like the sun, wind, water, etc. But people always make things difficult by not using these sources of energy. In the last few years there have been a great number of new ideas for generating（产生）energy. People suddenly realized that everyday things can be a source of energy. For example, riding a bike, running or just【2】, etc. But, is there anything else that can be used for collecting energy? We 【3】 have to change our way of thinking if we want to change the world.

So comes the idea of solar（太阳能）roadways. Are they the road of future? Why don't we use them for collecting energy?

The US Department of Transportation 【4】 $100,000 to Solar Roadways to build the first ever Solar Road.