Suffixes are letters that can be added to the end of words to change their meaning. Adding the suffix -ly, turns an adjective into an adverb. Well, what a nice game you've invented. You know, why ...

When you add a suffix to a word ending in 'fer' you sometimes need to double the 'r', but how do you know when? When you add a suffixes and the second syllable of the new word is stressed, then you ...