I
The letter A
M
The letter 'e'. It appears once in year, twice in week and never in day.
The letter 'e'. It appears once in year, twice in week and never in day.
The letter 'n'
M!
M!
b) Once The year was 2006.
the letter M
The letter "m" :DOnce in a minute, twice in a moment, and never in a hundred years.
The duration of Christmas Comes But Once a Year is 420.0 seconds.
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.