----Look at the boy running on the playground. Is it David? ---- It ______ be him. I saw him go to the teachers’ office just now.
— I missed the beginning of The Voice of China yesterday evening. —_________! But you can watch the re-play tonight.
What method can you think of _________ with these broken computers?
Scientists are trying their best to_______ ways to treat the terrible disease caused by Ebola(埃博拉).
—What shall we do this Saturday? —it rains, we’ll have a picnic in Century Park.
It's a pity that I didn't think of ringing you.