I've always been taught that a vowel before a double consonant following another vowel should have a short sound. Conversely, there are many situations where a vowel preceding a single consonant and vowel gets a long sound.
Mississippi - All I's except the last get short sound Communication - First O gets short sound Oppose - First O gets short sound where second O gets long
Ape - A gets long sound Popery - O gets long sound Oppose - First O gets short sound where second O gets long
Yet, I hear people use a short O in "operator" when using the word. Is this the correct pronunciation?