* Ham: The "a" in "ham" has a short sound, like the "a" in "cat."
* Skate: The "a" in "skate" has a long sound, like the "a" in "cake."
* Grape: The "a" in "grape" has a short sound, like the "a" in "cat."
So, to summarize:
* Ham has a short "a" sound.
* Skate has a long "a" sound.
* Grape has a short "a" sound.