Grammar Problem

[anthony_ball]

i have some problems about this question.

-The Colonel reported to the _____ office.

the blank can be
1. Chief-of-staff's
2.Chief-of-staff
3.Chief's-of-staff
4.Chief-of-staffs'

which option is correct????
please gice a detail solution.. thanks all!!!!!!

[Raymott]

Originally Posted by anthony_ball

-The Colonel reported to the _____ office.

the blank can be
1. Chief-of-staff's
2.Chief-of-staff
3.Chief's-of-staff
4.Chief-of-staffs'
[...]

1. is correct because you're referring to the office of the Chief-of-staff, and that's how we normally indicate the possessive in English.
2. is wrong because it's just not idiomatic. 'head office' or 'main office', but 'teacher's office' (if referring to the office of one teacher).
3. is incorrect for no other reason than we don't say it that way.
4. is incorrect unless there is more than one Chief-of-staff, which there usually isn't. But 'teachers' office' is correct if you're referring to the office of more than one teacher.