The letter "e"
fortnight
The letter 'n'
the letter M
The letter "m" :DOnce in a minute, twice in a moment, and never in a second.
the letter "A"
The letter "m" :DOnce in a minute, twice in a moment, and never in a hundred years.
The answer to this riddle is the letter "W". The letter "W" appears twice in a week (Monday and Wednesday) and once in a while (as in "once in a while"), but it never appears in a month because there is no "W" in the names of the months of the year.
fortnight
The letter O
The letter a
vowel
I
M
Nothing, its impossible!
The letter 'n'
M!
M!