Same with "bleeding" and "bleedding". We say "swimming", so why not "bleedding"?
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English orthography, while far from exhaustively consistent, can explain these constructions.
Produce has a long U, indicated by the silent E at the end. Adding a C in the suffix -ing (produccing) would indicate a short U. Also, while a C followed by an E, I, or Y is softened to an S sound, the first of a double C is usually pronounced as K (as in succeed) regardless of the softening of the second C. So produccing would sound like "pro-DUCK-sing"
/pro ˈdʌk sɪŋ/.
Swim has a short I, since no vowel comes after it to lengthen it. When the suffix -ing is added, an additional M is necessary, or else the first I is lengthened (i.e. swiming would be pronounced "SWYE-ming"
Bleed has a long E, indicated by a double E (you can think of it as the first E being lengthened by the second silent E). Adding -ing does not change the pronunciation of the original, no no additions are necessary.
As a general rule, when you add -ing to a verb, the result should be spelled so that the verb root is pronounced the same as before you added the suffix.
I am not sure if this is official English rule, but it exists and it is called a C-V-C rule - Consonant-Vowel-Consonant: when the last three letters of the verb form a CVC then you need to duplicate the last letter before adding the suffix. Let see your examples.
- Bleed - VVC - no doubling
- Swim - CVC - double 'm'
Remember not to apply this rule for suffixes starting with a consonant, for example if you form an adjective with -ful or -less, e.g.
- RegreTTing, but not regreTTful
The first rule for consonant doubling is that the simple vowels a e i o u are stressed and spoken short as in fat fatter, get getting, sit sitting, hop hopping, put putting, and shut shutting.
The logic of this rule is clear. Since English drops the final mute -e as in to hope, when you add an ending such as -ing you should spell it hoping and NOT hopeing. So with consonant doubling of one single consonsant after a simple stressed and short vowel we can distinguish hoping (to hope) from hopping (to hop).
This rule does not apply when stressed vowels are spoken long as in "to feel" (feeling) or if you have two consonants.
There is a second rule for consonant doubling: after long vowels, compare "to star", starring and "to stare", staring.
The third rule concerns simple final consonants in unstressed syllables. Compare "to travel", travelling (BrE). AmE doesn't observe this rule and spells it traveling.
A good grammar should have the rules for consonant doubling.