16. Emission of greenhouse ________ pollutes the environment.

A. air                B. gases            C. change

9. Online learning helps students explore a topic at their own ________ without rushing through it.

A. pace             B. chunk           C. cloud

3. Social ________ has changed the way we communicate with people all over the world.

A. systems        B. streaming     C. media

8. Technology helps students do their ________ easily using online materials.

A. education     B. learning       C. research

6. Nowadays, we can ________ information quickly using the Internet.

A. access          B. treat             C. detect

4. Eco-tourism is a great way to take a vacation and ________ your carbon footprint.

A. reduce          B. recycle         C. maintain

18. ________ off the lights when you leave a room. It saves energy and money.

A. Cut              B. Use              C. Turn