Insert a gap into a text field at runtime

Hi everybody,
it’s the first time i write in this forum. Please, forgive me for my english but i’m italian.
Here is the problem: i have to display some text from an external xml file.
The xml file is something like this:
<sentences>
<sentence>I’ve got <gap>blonde</gap> hair and <gap>brown</gap> eyes and I’m tall.</sentence>
<sentence>I like playing on my <gap>computer</gap>.</sentence>
<sentence>I like riding my <gap>bike</gap>.</sentence>
</sentences>

Instead of the content inside the <gap> tags, i have to display an input text field. So, for example the first sentence should appear like this:
I’ve got **INPUT TEXT FIELD **hair and **INPUT TEXT FIELD **eyes and I’m tall.
Any ideas?
Thanks everybody in advance.