A.I'm not satisfied with your explanation of where you <u>were</u> last night.
b.I came into the room when Mary <u>was playing</u> the piano.
c.no error!!!
d.There <u>are</u> some sheep in the field.
e.Playing the drums and singing<u> is </u>difficult.
Answer: C) Leave as is
Explanation: So, let's figure out the defenition of revision. Revision means to edit or form of something.
I really don't understand how the other options will make the sentence flow better, therefore it has to be C
Let me know if i'm right or wrong :D
Answer:
I do believe your answer is D: Most of Earth's mantle is always moving.
Hopefully this helped! :D