---Do you know_______ the books on the shelves? --- Sorry, I can’t count them, because there are _______books. A. a number of; the number of B. a number of; a number C. the number of; a number of
--- The pollution is becoming more and more serious in our hometown.
--- That’s right. We should do ________ we can to protect the environment.
A. nothing
B. everything
C. something