Change text background within paragraph (with automatic linebreaks)

How do I change the text color as well as the text background color for e.g. a sentence within a paragraph? I know \textcolor for coloring the font and \colorbox for background coloring [http://en.wikibooks.org/wiki/LaTeX/Colors]. Unfortunately \colorbox will not perform a linebreak. Is there any solution for that?

I want to make MY changes in a PDF document visible for review. I know some other approaches like diffpdf, oder pdftotext and then diff.. But I thought this should be an easy task.