[NTG-context] Cloze Text (text with gaps)

Hi list I wonder if I can typeset a cloze text using context. The gaps (__________) must have a given length (say in cm or the length of a given word, given sentence) and must break at the end of a line. \hl[4] is nice but won't do the trick since it won't break. \fillinline and others fill the hole line, but I only want to fill a given size. Are there some ideas how to deal with it? Example: The name of the _____________ is _____ ________. And now it's time to go to bed. Some more text..... Hope you get the point. Thanks in advance Christian PS.: For Latex there is a package: http://tex.stackexchange.com/questions/79689/control-ulines-for-cloze-text