f, g, s, y — 4 letters, 10 sounds
One of the complications of written English is that some sounds can be represented by more than one letter.
Each of the letters f, g, s, and y represents a distinct speech sound. In addition, these four letters can also be used as alternate spellings for sounds that already have distinctive letters of their own.
Ff
/f/ as in fan
The letter f is also an alternate spelling for /v/ as in of.
Gg
/g/ as in get
The letter g is also used as an alternate spelling for the sound /j/ as in giant.
S/s
The sound represented by the letter s is /s/ as in sip. The letter s is also used as an alternate spelling for the sound /z/, as in rose.
Y/y
The letter Y represents a unique consonant sound when it occurs at the beginning of a word as in yellow.
Y is also used to represent the short i sound, as in myth, the long i sound, as in my and the long e sound at the end of words, as in happy.