What is the letter before "H"? What is the letter after "H"? What are the Roman numerals?  Is it the case that not both #1 and #2 are in #3?
H
The Roman numerals are: I, V, X, L, C, D, and M. The letter H in the alphabet is preceded by G and followed by I.
letter in the Latin alphabet
Are any letters directly before and after H missing from Roman numerals?