Why this DTFT plot from CTFT?
When a continuous time signal is sampled in discrete intervals, the effect in the frequency domain is that the CTFT becomes periodic in frequency - that is, you end up with "copies" of the original CTFT, with each copy centered at frequencies equal to k*1/T (k = any integer). 

So, when you sample at 12/pi you will get a copy of the original CTFT centered at w=0, w=12/pi, w=-12/pi, w=24/pi, w=-24/pi, and so on.

Since you have frequency content between 2&lt;|w|&lt;4 in the w=0 case, the w=k*12/pi cases will have frequency content between 2&lt;|w-k*12/pi|&lt;4.

Be careful - if frequency content from multiple copies have frequency content in the same places on the frequency axis, the effect is that they add together.  This is called "aliasing" and is usually an unwanted effect of sampling.

Here is a nice graph that shows the effect of sampling a continuous time signal on the FT.