static LS tok_remainingPhrases(LS tok, BitSet marked) {
  new LS out;
  for (int i = 1; i < l(tok); i += 2) {
    if (getBit(marked, i)) continue;
    int j = i+2;
    while (j < l(tok) && !getBit(marked, j))
      j += 2;
    out.add(joinSubList(tok, i, j-1));
    i = j;
  }
  ret out;
}