The vowels missing in "bliv" are "a" and "e".
i
The vowels missing in "slmndr" are "a" and "o."
The missing vowels in "xprts" are "e" and "o".
To me it looks like the original word was "Insatiable", so it would just be two "I"s that are missing. One at the beginning, and one after the "t".The letter is I (insatiable). Some in- or un- words may use both spellings.
Torts, tarts, traits, treatise, treats, treaties, tortoise, trouts
That collection of letters isn't a word. If you meant "insatiable," the final "e" isn't pronounced.
The words that could be spelled are earths and quartet.
Rake perhaps?
Oxyuridae. A group of worms. That is the only thing i can find. Your answer isn't hippopotamus.... I'm sure you noticed it was missing the e.
long vowels and short vowels are both just vowels they can't have more or less of themselves
This is likely a pony. If you want to get technical, a Y is sometimes considered a vowel. That is used as a diversion to get people to ignore the most obvious answer. Also, saying that it has a P and an N in it and that vowels are left out does not imply that there are no missing consonants.