—I’m not sure ______there are living things on other planets or not .—Even scientists aren’t sure about it.
—It’s raining. Do you have an umbrella? —No, but Lucy has __________.
Every day, students bring their schoolbags __________ school.
—__________ socks are they? —They are __________ socks.
Who is the man __________ long hair.
__________ your books and look at the blackboard.