The letters in the second group sound similar to the word "see":
B, C, D, E, G, P, T, V.
The letters in the third group sound similar to the word ten:
F, L, M, N, S, X.
The letters in group number 4 sound similar to the word "drive":
Then there is the letter O as in the word "home".
In the next group the letters sound like in the word "too":
Q, U, W.
And finally there is the letter "R" which jsounds like the word "car", "bar", "scar".