China is expected to export 1 billion mobile phones this year, ________ by a surge in demand for smartphones worldwide.
Who is it up ____ decide whether to go or not?
Wang Mei is one of many Chinese teenagers _____ “on the go”
The two boys fought and fought until one ______.
He will _____ our class to sing at the school singing contest.
They told us that these small apples are often sweeter than big ____.