1. Solar generation __________ up only 3.3 % of total U.S. generation in 2020.
A. made                       B. makes                     C. is making                D. will make
2. Energy __________ from different forms and essential for everything we do.
A. comes - is                B. come - be                C. came - was             D. come – are
3. Trees __________ in carbon dioxide and it in their trunks.
A. breathes - store      B. breathe - store        C. breathe - stores      D. breathe – stored
4. The Greeks __________ water wheels to grind wheat more than 2,000 years ago.
A. use                          B. uses                         C. used                                    D. are using
5. Nowadays, renewable energies __________ on a very important role in the heating market.
A. took                         B. takes                       C. is taking                  D. are taking
6. Many countries in the world __________ wind power on a commercial basis today.
A. used                                    B. will use                    C. are using                 D. uses
7. Now automakers __________ fuels cells that extract hydrogen from gasoline.
A. developed               B. develops                  C. are developing        D. will develop
8. In the old days, humans __________ on the sun and wood for heat.
A. rely                          B. relies                       C. are relying              D. relied
9. Hydroelectric, wind, solar, biomass and geothermal energy __________ all limitless.
A. is                             B. are                          C. will be                     D. was
10. Today, the world's resources __________ at an extremely fast rate.
A. are depleting          B. depletes                  C. depleted                  D. is depleting