Question

A team of explorers ___________ the ocean floor. (1 point)
were studying
are studying
have been studying
has been studying

Answer 1

It is in the present tense. So I would say, are studying.

Answer 2

Okay!

Answer 3

Both light and heat _________ causes of the sofa's fading color. (1 point)
was
were
is
is

Answer 4

Are there two is's?

Answer 5

Or is one supposed to be are?

Answer 6

Because, I would say: Both light and heat are causes of the sofa's fading color.

Answer 7

No its Is and isn't.

Answer 8

Then I would have to say it is in a past tense, meaning it would be were.

Answer 9

Physics ______ a very interesting subject to study. (1 point)
is
are
were
aren't

Answer 10

Saying it out loud, is sounds grammatically correct.