Some scientists think that it may take ______ years to make robots look like people, and do the same things as us.
What can we students do _____ the environment?
There are five people in the room, but I know _____.
—What did our geography teacher say?—She told us that the earth _____ around the sun.
—Lily, _____ you _____ your ticket?—Not yet!
We couldn’t wait _______ a good rest after the exam.