An unaccented vowel is called a schwa. It is represented by the symbol /ə/ in the International Phonetic Alphabet and is commonly found in unstressed syllables in English.
Atonic
The unstressed vowel in "abandoned" is the schwa sound, which is symbolized by the upside-down 'e' symbol /ə/. It is pronounced as a quick, mid-central, unaccented vowel sound.
No, the "liter" does not have an R-controlled vowel sound. In this word, "i" makes a short sound /ɪ/, and "e" makes an unaccented schwa sound /ə/.
An unaccented schwa is a neutral vowel sound represented by the symbol /ə/ in the International Phonetic Alphabet (IPA). It is often heard in unstressed syllables, such as the first syllable of "sofa" or the second syllable of "banana."
The schwa vowel sound in "challenge" is the short and unstressed "uh" sound. It is commonly represented by the symbol ǝ in the International Phonetic Alphabet (IPA) and is found in the second and last syllables of the word "challenge."
It has an unaccented short i sound. The oo is pronounced as in book, which is the short version of that vowel combination.
Atonic
The schwa vowel sound in "challenge" is the short and unstressed "uh" sound. It is commonly represented by the symbol ǝ in the International Phonetic Alphabet (IPA) and is found in the second and last syllables of the word "challenge."
The second and third syllables are unaccented.
An iambic foot has an unaccented syllable followed by an accented one.
dactyl
Atonic
A metrical FOOT (not a metrical set) is a pattern of accented and unaccented syllables, so false.
Over a long vowel it is called a breve, and over a short vowel, I believe it is called a circumflex.
The first.
a short vowel
Any vowel from (a,o,u) combined with (e,i) will result in a dipthong if there is no acent mark, i.e. ae, ai, oe, oi, ue, ui. Admittedly, ai, oi, ue, and ui are more common than ae and oe.