I'd like to create an "answer blank" in a document. It should basically look like an underline with nothing above it. I found a question about it ( [How does one TeX a blank?](https://tex.stackexchange.com/questions/7473/how-does-one-tex-a-blank) ), but that doesn't deal with the main problem I'm having, which is that I want the blank to wrap normally to the text width. The solutions using \hspace or \rule cause the line to extend into the margin.

I'm looking for something that wraps just like normal text and so won't extend into the margin. It should be an underlined blank that has a specified length, but that length might be wrapped across multiple lines in the output document.