The word narrow implies long and thin, as does slender.
The I has a short I sound as in this and twin. The long I would be the archaic term thine.
The I has a short I sound, as in thin and tint.
The I has a short I sound, as in thin and tint.
"River" is a short vowel word because the "i" sound is not elongated.
The word "tune" has a long vowel sound because the "u" is pronounced like "yoo" and not like "uh."
Not the word "in" which has a short i sound (ihn) as in bin, chin, and thin. The i can have a long E sound only (sometimes) when there is a silent E (marine, chlorine, ravine).
Some would be... washing, telephone, short, long, thin, blue, red, wavy, jagged, railway.....
Short
A short 'a'. A long a would be for example in the word 'farm'.
The word "wiper" has a short "i" sound.
The word "mitt" has a short i sound.
The word "ruby" has a long vowel sound for the letter "u" which is pronounced "oo" like in "blue" or "true".