6. old to run fast

young enough to run fast

7. fast for us to understand

9. this work was very boring

10. them 6 months to build this house

11. English well is very interesting

12. Nam half an hour to do this exercise

13. expensive for us to eat in

an expensive restaurant that we can't eat in

rich enough to eat in that expensive restaurant

1. Only when his father threatened to punish him did the boy tell the truth.

2. Only when she received that new treatment did the patient's heart condition improve.

11. B. because of

12. B. even though

13. C. too

14. B. enough

15. C. such

16. B. such a

17. C. intelligent enough

18. B. too

19. A. so

20. C. interesting enough

17. B. so many stars

18. A. so much work

19. A> too

20. D such an old

21. D in spite

22. C because