Should AN be written before all words starting with an F?

No, "AN" is not written before all words starting with an F.

Here's why:

* Sound: "AN" is used before words that start with a vowel sound, even if the first letter is a consonant. This is because the sound the word makes is more important than the actual letter.

* Examples:

* An apple (The "a" in "apple" makes a vowel sound.)

* A friend (The "f" in "friend" makes a consonant sound.)

* An hour (The "h" is silent, so the "o" makes the first sound.)

Let me know if you have any other questions!