15. How long they
(to date) before they got married?
a) had they dated
b) were they dating
c) had they been dating
d) have they dated
have they been dating
16. I don't think I
go out tonight. I'm too tired.
a) will go out
b) would go out
c) go out
d) will be going
17. He
(to work) on a new play during this summer.
a) work
(b) will work
c) will be working
d) would work
e) is working
18. Choose the correct form of the verb in the Passive Voice: Many accidents
(to cause) by dangerous driving.
a) caused
b) is caused
C) are caused
d) have been caused
e) will be caused.
19. Look, trees
(to plant) by the children in our yard.
a) is planting
b) planted
c) is being planted
d) was being planted
e) are being planted
20. The house
(to buy) for 5 thousand dollars.
a) bought
b) has been bought
c) was bought
d) is being bought
e) was being bought
21. The test
(to write) by our students before the bell rang.
a) was written
b) is written
c) has been written
d) had been written
e) was being written​