Yes, they're all consonants, but that's not what we're looking for. And yes, I'm certain some of you will find alternate answers. And that's okay. Because I'm good enough, I'm smart enough... Sorry, I was channeling Stuart Smalley there for a moment. (I have that right; I paid to see Stuart Saves His Family in the theater. To be fair, I was in love at the time and wasn't interested in actually watching the film as much as I was being in a dark, empty theater.)

What (specifically) do these three
two-letter groupings have in common?

1.  B-G

2.  P-T

3.  T-N

HERE is the solution.

THE ANSWER: Each set can be made into five different words by adding the five vowels (A, E, I, O and U) between the letters. 

1. BAG, BEG, BIG, BOG, BUG
2. PAT, PET, PIT, POT, PUT
3. TAN, TEN, TIN, TON, TUN

Can you think of any others? Feel free to add them in the comments!