8, They haven't sung together since last concert
9, I could hardly understand what you said
10, It took the students two hours to correct their exercises
11, We used to play soccer for school team 
12, He used to go bowling on Sunday evening
13, We wish it didn't rain heavily so we can't go out
14, It;s time you learned to look after your self
15, I'd rather you stayed at homme this Christmas
16, He wishes his neighbors were friendly
17, She started working in this factory in 2001
18, If only he wrote to his friends
19, I forgot to do the exercise so I was punished by the teacher
20, I love cold weather and flowers very much so I live In Da Lat