Final answer:
Combining stems and suffixes that involve the transition from 'y' to 'ie' symbolize the long 'e' sound, as exemplified in the word 'galleries' from 'gallery' and 'es'.
Step-by-step explanation:
When combining stems and suffixes in words, it is important to note the correct spelling of certain letter combinations that represent specific sounds. For example, the sound [ē] is often represented with the letters ie when a stem ending in y is joined with a suffix that begins with e. A good illustration of this rule is the combination of the stem gallery with the suffix es to form galleries, underlining the transition from y to ie to represent the long e sound.