Bài 2:
1.Maria was writing poems at that time
Poems 
2.Sarah was writting a letter when I came
A letter
3.We use this room only on special occasions
This room
4.A Japanese firm makes these TV sets
These TV sets
5.My sister cleans the room every day
The room
6.They grows rice in this field every year
Rice
7.They don't make planes here
Planes
8.The police shouldn't allow people to park here
People
9.People mustn't leaves bicycles in the hall
Bicycles
10.The manager must sign the check
The check
11.They are going to open a new school here next month
A new school
12.We cleaned this room yesterday
This room