---Look! The light is still on. Is Mr Wu working in his office?---No, it _____ be Mr Wu. He has gone to Nanjing for a meeting.
______ exciting news! We’ve never had ______ long vacation before.
It will ______ us several years to learn a foreign language well.
I heard that two new ______ would come to our school two days later.
--Can you tell me ______?--Sorry, I don’ know. If he _____, I’ll call you.
--What was your sister like?--She ______ be quiet, but now she is more outgoing than me.