2. (+) This was my teacher.      

(-)..           This wasn't my teacher

(?)           Was this your teacher                                                                                     

3. (-) Thu and Lan weren’t students.   

(+) Thu and Lan were students.

(?)Were Thu and Lan students.

4.   (?) Was it a chair?                

(+) It was a chair

(-) ……It wasn't a chair………………………….……

5. (+) My school Was small.    

(-) My school wasn't small…………………………………….

(?)..Was your school small.………………………….………….?

6. (+) We were from Vinh city.       

(-) ……We werent' from Vinh city……………………………

(?)...…Were you from Vinh city………………………...……

7. (-) He wasn’t eleven years old     

(+) ……He was eleven years old      …………………………………... 

(?) ……Was he eleven years old     …………………………… ?

8. (+) These were desks.           

(-) ……These weren't desks………………………………..……..

(?) ……Were these desks……………………………………..?