This is not the case, however. Instead, the ad will show for the keyword or keyword phrase plus other words that are likely to be relevant.
Excerpting from the AdWords Help Center (italics added) @ [adwords.google.com...] :
Phrase Match - If you enter your keyword in quotation marks, as in "tennis shoes," your ad will appear when a user searches on the phrase tennis shoes, in this order, and possibly with other terms in the query...
A quick tip: if there are variations that you know you'd like to appear on, it's a good idea add them to your keyword list as keywords in their own right.
AWA
<edit> Hit 'submit' rather than 'preview', while still editing. Oops. </edit>
[edited by: AdWordsAdvisor at 5:11 pm (utc) on Oct. 12, 2006]