What is Lucy doing now?—She _____ a book.
―I wonder _______they are waiting.―At the bus stop.
Have you got any books on English grammar? I want to borrow______.Yes, here you are. But you must return it by Friday.
Excuse me, could you tell me _______?—Sorry, sir. I wasn’t there at that time.
The river smells so terrible! How did it come about?—People used to pour dirty water into it.