dualSwitchSentence_improved.js

var status = {
  'worker'  : 0,
  'student' : 1,
  'fish'    : 2
};
var time = {
  'morning' : 0,
  'evening' : 1,
  'night'   : 2
}
var text = [
  ['get ready for working!', 'work hard!', 'sleep well for tomorrow!'],
  ['sleep till noon...', 'have breakfast', 'play video games'],
  ['swim slowly', 'swim quickly', 'swim very slowly']
];
function whoDoesWhat_short(a, b) {
  var who = status[a];
  var what = time[b];
  console.log(text[who][what]);
}

whoDoesWhat_short('worker', 'evening'); // work hard!