II. Put the verbs in the brackets into the present continuous or the present simple.

1.The Sun __________ (be) the main source of energy on Earth.

2.How many types of energy __________ (humans, use) at present?

3.My father __________ (replace) the old bulbs in my room at the moment.

4.It __________ (take) billions of lifetimes for new fossil fuels to form.

5.At the current time, many families __________ (look) for ways to use less energy.

6.We __________ (discuss) about the advantages of some energy sources now.

7.Today, governments __________ (face) multiple challenges of energy security.

8. __________ (you, visit) the biggest hydropower dam in the country at the moment?

9. Nowadays, critical changes __________ (take) place in the global energy system.

10.We'll choose electric vehicles if they __________ (be) more convenient and cheaper.