Don’t you know it’s ______ useful book for English learners?
I’m not good at Maths, so I don’t know _________ out this difficult Maths problem.
---Your sister _________ a lot during these years. ---Yes. She _________ three years ago.
I _________ great progress in English since I _________ reading novels in English.
To the students, it’s _________ to enjoy a video during the class.
---Have you seen Mr. King these days? ---No, he _________ Shanghai for an international meeting. He’ll come back in three days.