JS/Node.JS Poem Generator (Followup)

Original question: Node.JS Automatic Poem Generator

This is a followup to the question from above. I am only reposting, as my new code was written from the ground up, and is only slightly similar.

This code generates (sentences of) random poems.

// Node.JS/JavaScript Poem Generator
// This only generates simple sentences, not full poems.

// First of all, we need some words. I don't include every part of speech; just the useful ones.
// In addition, I mostly chose words that were abstract, pertaining to emotions, or artistic.

// a = noun singular
// b = noun plural
// c = pronoun singular
// d = pronoun plural
// e = verb action
// f = verb linking singular
// g = verb linking plural
// h = adjective
// i = adjective possessive
// j = interjection
// k = preposition
// l = adjverb

var
a = "darkness,morning,light,feeling,beauty,love,hatred,expression,message,happiness,sadness,anger,frustration".split(","),
b = "mornings,lights,feelings,beauties,messages".split(","),
c = "he,she,it,I".split(","),
d = "them".split(","),
e = "ran,went,vanished,died,lived,appeared,disappeared,increased,decreased,augmented,changed".split(","),
f = "is,was,had been,will be,could be,might be,should have been,would have been,could have been,should be,would be".split(","),
g = "are,were,had been,will be,could be,might be,should have been,would have been,could have been,should be,would be".split(","),
h = "abstract,mysterious,permanent,unfortunate,intricate,confusing,true,false,fake,a lie,a stranger,a friend,serene,confusing,an enemy,terrible,enchanting,mine,yours,his,hers,theirs,ours,fortunate,understood,mine,interesting,mutual,artistic,musical".split(","),
i = "the,my,your,his,her,their,our,everybody's".split(","),
j = "ha,ah,aah,eh,er,hmm,yah,oh".split(","),
k = "with,from,during,included,among,by,about,between,after,along with".split(","),
l = "quickly,fleetingly,continuously".split(",");

// A short helper function to generate a random word based on the type given to it.

function newWord(type) {
  switch (type) {
    case "a":
      return a[Math.floor(Math.random()*a.length)];
    case "b":
      return b[Math.floor(Math.random()*b.length)];
    case "c":
      return c[Math.floor(Math.random()*c.length)];
    case "d":
      return d[Math.floor(Math.random()*d.length)];
    case "e":
      return e[Math.floor(Math.random()*e.length)];
    case "f":
      return f[Math.floor(Math.random()*f.length)];
    case "g":
      return g[Math.floor(Math.random()*g.length)];
    case "h":
      return h[Math.floor(Math.random()*h.length)];
    case "i":
      return i[Math.floor(Math.random()*i.length)];
   case "j":
      return j[Math.floor(Math.random()*j.length)];
    case "k":
      return k[Math.floor(Math.random()*k.length)];
    case "l":
      return l[Math.floor(Math.random()*l.length)];
  }
}

// To make the program more modular, you can create sentence structures and call them with this
// function. It takes a string such as "i a f h.", and replaces the lower case letters with
// a new word, as chosen by the above function.

function newSentence(format) {
  var sentence = "";
  for (var token = 0; token < format.length; token++) {
    if (-1 == "abcdefghijkl".indexOf(format[token])) {
      sentence += format[token];
    } else {
      sentence += newWord(format[token]);
    }
  }
  return sentence.charAt(0).toUpperCase() + sentence.slice(1);
}

// Right now, the code only uses one sentence structure, but can interpret many more.

console.log(newSentence("i a f h."));

In my previous post, the only response I received was pertaining to the poems themselves. Although the advice was appreciated, I am more concerned about the code itself.

Several things bug me about this code already, but I don't know a more elegant solution:

1. The newWord() function seems unnecessary. Using eval() could make the code a lot shorter and more elegant, but everything I have learned about JS has told me to avoid eval() at all costs.

2. Is a CSV really the best way to define a list. Defining a list in a normal was (["he","she","it","I"]) is much longer.

Any advice would greatly be appreciated.