Question

They __ a new power station at the moment.
A) were building B) are building C) is building b) build​

Answer 1

Answer:

B) are building

Hope it helps :)

Answer 2

They are building a new power station at the moment.

Explanation:

1.Since at the moment appears in the sentence.It is present continuous tense.

2.They means plural.Hence "are" should come.

3."At the moment" is used to indicate that a particular situation exists at the time when you are speaking.

4.So "building" should come instead of "build".

5.Since it is in present continuous tense "were" is avoided.

6.These are some basic grammers of English.