A.c, a, b, d | B. c, b, a, d |
C.b, c, a, d | D. c, a, d, b |
A.build up more power stations in the world |
B.provide cheaper energy for developing countries |
C.offer people in developing countries access to pure water |
D.gain a deeper understanding of the photosynthesis process |
A.an introduction to the history of artificial leaves |
B.a mixture of water power and solar energy |
C.giving energy to the poor |
D.an invention copying photosynthesis |