we usually use "an" before vowels, but why for "MRI"?

Answer 1

I would assume that image is the noun in question and the other two words are considered modifiers.

So it is "an Image".

Answer 2

A vowel is used before most abbreviations because of the spelling of the actual letters. For example, in MRI, the first letter is M, spelled "em" which required a vowel. In the case of TWA, however, you would use 'a' since T is spelled "tee"

Answer 3

The version of the rule you've been taught is slightly off.

The rule is that you use "an" when the following word begins with a vowel SOUND, not necessarily a vowel LETTER.

In most cases there's no difference except:

1) words whose first consonant is silent (mainly "h") take "an", because they begin with a vowel SOUND

example: "honor" ("It's an honor to meet you.")

2) words that begin with "u" or (especially) "eu" that make the CONSONANT "y-" sound are preceding by "a"

examples: ukulele, euphoria

3) pronouncing letters -- if you begin with a vowel sound, use "an" before it; if you begin with a consonant sound, use "a" before it

examples:
.... use "an" a ("ay"), e, i, l ("el"), m ("em"), n, r, s, x
.... use "a": all the rest! but esp. notice -- u (like "you"), y (like "why")

Answer 4

The actual rule is quite a bit more complicated and distinguishes between speaking and writing and also between a vowel and a phonetic vowel (or consonant and phonetic consonant). "M" is a consonant, but it is pronounced "em" which makes it a phonetic vowel. So you would write "a MRI" but would say "an MRI".

Answer 5

Use "an" before MRI because "m" is pronounced "em"...kind of like it begins with a vowel itself. Same situation with "s" (ess), "l" (ell), "n" (enn) "f" (eff), etc. Don't think of the leter itself, think of the sound it produces...if it sounds like it begins with a vowel, then use "an".. Hope this helps.

Answer 6

As explained by yourself, "an" is used before a vowel AND vowel sounds. Therefore, as mentioned previously, the letter M sounds like the sound in 'EMergency' and you would say, "I have AN EMergency". Get it? (... or EMily, EMmanuelle, etc.)

Answer 7

We use "an" before "MRI" because it starts with the letter "M". "M" has two sounds..... short e and mmmmm. The short e sound is a vowel sound; so we must use "an".

Does that help? :)

Answer 8

Though "an" rule applicable only for vowel, it also good for those shortforms (like yours MRI) which sounds with vowel as "EM". An "SRP" van.... An "FBI" Agent....An "HIV" patient...An..."NRI" citizen....are some other examples of this category.

Answer 9

I believe the only cases where "an" precedes a word beginning with H is historic and historical.

Answer 10

Because 'M' is pronounced "EM" - meaning it begins with a vowel sound.

Answer 11

simple: "an" is used in front of vowel sounding words, not all vowel words.