What do all of the following words have in common?

GAPE         OLE

ROME        HOSE

JUDE          LIEN

CRIME       RODE

SMILE       ARE

CAME 

Answer:

 

They are all one-syllable words that become three-syllable words with the addition of a vowel:

 

AGAPE       OLEO

ROMEO      HOSEA

JUDEA        ALIEN 

CRIMEA     RODEO

SIMILE       AREA

CAMEO