I think the question needs rewording.
In English, a consonant, vowel, consonant sequence creates a short vowel.
Take my name: Sam
to make the vowel long, we add the silent "e" to the end
Sam becomes Same
Silent "e" makes the preceding vowel say it's name
To elongate a vowel differently we use the consonants r and w
fat becomes fart (for example)
No, the word "base" does not have a long vowel sound. The "a" in "base" is pronounced as a short vowel sound.
The long vowel in "stomachache" is the 'a' sound in "ache."
The first E is long, but the second is unstressed (schwa).
Diesel does have a long "E" sound, so yes. Generally in long vowel words with two vowels together, the long vowel sound represents the first letter of the vowel pair, not the second, for example "died," where the long vowel sound is "I" So "diesel" is unusual, since the long vowel sound represents the second vowel "E"
The long vowel in "dehydrated" is the letter "a" in the second syllable.
Yes. The first I has a long I as in dine, and the second has a short I sound.
The first E is long, but the second is unstressed (schwa).
Yes, "mail" contains a long vowel sound in the second syllable.
The i in timer is a long vowel and the e in timer has a short vowel.
"Climate" has a long vowel sound in the first syllable ("cli-") and a short vowel sound in the second syllable ("-mate").
in-SPIRE-rer the first vowel is short, the second vowel is long, and the third vowel is hardly pronounced.
First syllable long, second syllable short