Tritone Substitution

Question 1

Define..

Answer 1

Replace one or more of one of the elements of 2/5/1 with a chord of the same type but built on a root a tritone away from the chord being replaced; this changes the progression to a root a perfect 5th lower into one with a root A HALF STEP LOWER
Dmi7 G7 Cmaj7

Dmi7 Db7 Cma7

Question 2

Replace 7th with TT sub for 251 in C

Answer 2

Dmi7 Db7 Cma7 ii, bII7(of 1), or bV7/V or subV7(I) or V7/bV(I)
tritone substitution involves replacing V7 with ♭II7[1] (which could also be called ♭V7/V, subV7,[1] or V7/♭V[1]). For example, D♭7 is the tritone substitution for G7.

Question 3

2 sub5 1 in F

Answer 3

Gmi7 Gb7 Fma7