Mr Liu is ____ unusual teacher. He has written _____ useful book for his students.
When I returned .I saw him ____ on the bed.
Our teacher ____ in our school for 29 years and he ____ here when he was 23 years old.
---Look, Sue is over there. --- That ____ be her. She is in Canada now.
---Would you mind my sitting next to you ? ---_______
---Jim isn’t in the classroom. Where is he? --- He ____ to the teacher’s office?