See, for example:
https://www.msofficeforums.com/word-...html#post33489
https://www.msofficeforums.com/word-...tml#post107008
Anyone requiring a solution in a document using content controls for anything else is likely to also require checkbox content controls. Since Office 2007 doesn't support checkbox content controls, you won't be able to fulfil the requirement without upgrading Office to at least Office 2010. Otherwise, you'll have to craft something similar using formfields - but that may not be acceptable, either. Note that you should not use formfields and content controls in the same document.

In any event, IMHO, you'd do better to use a dropdown with Yes/No options.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]