Riff 1 tremolo picking

  d------------------------------------------------------------------
  a------------------------------------------------------------------
  f------------------------------------------------------------------
  c------------------------------------------------------------------
  g-----5-7-8-7---3-5-3---------------------5-7-8-7---3-5-3-----7----
  D---5-------------------7-8-7-3--------5------------------7-8---8--

  Riff 2 tremolo picking     

  ----------------------
  ----------------------
  ----------------------
  ----------------------
  ---7-8-10---5-8-7-----
  ----------------------


  Riff 3 tremolo (not sure about this one)

  ------------------------------------------------------------------   
  ------------------------------------------------------------------
  ---------------------------5----5---------------------------------
  ----7-----7-------------------------------------------------------
  ----------------7--------3----3---------5----3--------------------
  -5-----5----------8-7-----------------3----1----------------------