How to infer possessiveness

0Hi,02br
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00I sometimes have a hard time knowing whether a phrase is written in possessive or not. Usually, possessive shows the ownership, I think. Do you have any tips? How about this, which one shows the best example? 02br
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00Supervisor's Office 02br
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001. an office 01u00of 02u00the supervisor, assuming there is only one supervisor??02br
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002. an office 01u00for02u00 the supervisor, assuming there is only one supervisor??02br
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003. an office 01u00owned by02u00 the supervisor, assuming there is only one supervisor??02br
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00The above may be a simple case but there seem be many dubious cases where a simple application of the above method may not be all that useful. Do you have any tips? 0-