sentence(Num)-->noun_phrase(Num),verb_phrase(Num).
verb_phrase(Num)-->verb(Num),noun_phrase(_).
noun_phrase(Num)-->determiner(Num),noun(Num).

determiner(singular)-->[a].
determiner(singular)-->[the].
determiner(plural)-->[the].

noun(singular)-->[cat].
noun(plural)-->[cats].
noun(singular)-->[mouse].
noun(plural)-->[mice].
noun(singular)-->[moose].
noun(plural)-->[meese].

verb(singular)-->[scares].
verb(plural)-->[scare].
verb(singular)-->[hates].
verb(plural)-->[hate].