%:- [any].
%
%paras(N) :- forall(between(1,N,_), show(W,words(W))).
%
%words(W) :- once(sentence(W,[])).

sentence --> nounphrase,verbphrase.  

nounphrase --> [the, boy]
             | [the,girl].           

verbphrase --> verb,modlist,adverb.

verb --> [runs] 
       | [walks].             

modlist --> [] 
          | [very],modlist.     

adverb --> [quickly] 
         | [slowly].