Show, again, that the time delays for the emission of the
transmitted and relfected packets, 
and 
, are identical.
Hint: Again, there is no need to compute them explicitly to show this.
Make a sketch in the complex plane of the behavior of 1/t(k), the inverse of the transmission amplitude, as a function of k for very large D. Mark on your sketch the points corresponding to resonant tunneling. What does your sketch indicate about the time needed for such a tunneling event to occur for large D? (Note that the phase angle of 1/t(k) is just minus one times the phase angle of t(k).)