Exercise 2:

1, was caught

2, is read

3, was cut

4, was being cleaned

5, is going to be built

6, has been already typed

7, ought to be typed

8, was being taught

9, are caused

10, is being repaired

Exercise 3

1, was invented

2, worked

3, was introduced

4, became

5, was

6, was used

I

1, since

2, for; since

3, for

4, since

5, for

6, for

7, since

8, since

9, for; since

10, for; since

III

1, have had

2, have lived

3, went

4, stayed

5, haven’t seen; hasn’t visited

6, has been

7, have worked

8, have moved; have been

9, have already gone

10, wore

11, have moved; got

12, have played

13, have not seen; met

14, Has Bill arrived; arrived

15, studied

IV

1, We haven’t heard from Sarah since she moved to Atlanta.

2, Sandra has worked for that company for three years.

3, My father hasn’t seen my uncle for nearly twenty years.

4, Juliette started teaching in this school in 2009.

5, Christopher wanted to buy that TV yesterday.

6, Mathew traveled to Germany 3 weeks ago.

7, Minh enjoyed the school play last Saturday.