11. You should use electric fans instead of air conditioners ____ they don't emit dangerous gases.
A. so B. but C. because D. although
12. Kevin told Phong ____ for many years.
A. plastic had been popular material for containers
B. plastic would be popular material for containers
C. plastic has been popular material for containers
D. plastic was popular material for containers
13. Kevin told Phong, ____ to our environment in several ways.
A. plastic may be very harmful B. plastic had been very harmful
C. plastic is too harmful D. plastic was very harmful
14. He ____ we could buy or make reusable bags and leave some bags in our bike for shopping.
A. said us B. says to us C. told us D. told to us
15. My mother encouraged me ____ for recycling.
A. to collect B. collecting C. collect D. should collect
16. The campaign ____ things like water bottles and aluminum cans into new, useful objects like park benches, bikes, etc.
A. becomes B. recycles C. turns D. comes
17. Fish and poultry have a much lower impact ____ the environment, and other plant proteins are even less damaging ____ the planet.
A. on - to B. on - with C. x - for D. of - to
18. We get the energy we require for our everyday needs from many sources, but not all of them are ____.
A. ecological B. economic C. unharmed D. eco-friendly
19. Burning garbage ____ dangerous gases to the environment, and this may lead to global warming.
A. emits B. throws C. sends D. rejects
20. Individually wrapped candy or chocolate causes a lot of trash, ____ fruits and vegetables are healthier and mean less waste.
A. because B. while C. so D. as
