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9. Remember to
the lights before going to bed.
A. turn
B. turn off
C. turn on
D. stop
10. A hydropower station
in the North of the country next year.
A. was built
B. were built
C. will be built D. has been built
and cheap for cooking and heating.
C. serious
11. Biogas is
A. plenty
B. abundant
D. expensive
12. What should we do to
electricity?
A. cut
B. take
C. save
D. waste
13. We are looking for cheap, clean and
sources of energy.
A. effective
B. efficient
C. serious
D. dangerous