1. These students talked too much in class

=> I wish these students  hadn't talked too much in class

2. We had a lot of homework yesterday

=> I wish we hadn't had a lot of homework yesterday

3. They won't come here  again

=> I wish they would come here again

4. It was cold last night

=> I wish it  hadn't been cold last night

5. They work slowly

=> I wish they didn't work slowly

6. She doesn't join in the trip

=> I wish she joined in the trip

7. I am not good at English

=> I wish I were good  at English

8. He studies badly

=> I wish he didn't  study badly

9. We didn't understand them

=> We wish we understood them

10. Today isn't a holiday

=> I wish today were  a holiday

11. I can't sing this song

=> I wish I could sing this song 

12. He was punished by his mother

=> I wish he hadn't punished by his mother

xin 5 sao và cthh ạ,mình cảm ơn

3 they won't come here again.

=> i wish..they would come here again.......

9 .we didn't undersyand them.

=>we wish............

12 He has punished by his mother.

=> I wish.....he hadn't punished by his mother.....