happening 为什么不双写n?可不可以详细说明加ing的具体规则?

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Rule 1: Words ending with a Consonant-Vowel-Consonant Pattern
(Review Consonants and Vowels)
One-syllable words:
ED = If the word ends in a CVC pattern, it gets a double consonant + ED. * note
ING = If the word ends in a CVC pattern, it gets a double consonant + ING. * note
Examples:
ED = RUB > rubbed, STOP > stopped
ING = HOP > hopping, SIT > sitting
*note: Words ending in w,x,y,z do not follow this rule, simply add ED, or ING
Examples: snow > snowed, box > boxing, play > playing
Two-syllable words:
ED = If the stress is on the first syllable, the word only gets one consonant + ED.
ING = If the stress is on the first syllable, the word only gets one consonant + ING.
Examples:
visit > visited, open > opened
happen > happening, enter > entering
ED = If the stress is on the second syllable, the word gets a double consonant + ED.
ING = If the stress is on the second syllable, the word gets a double consonant + ING.
Examples:
refer > referred, admit > admitted
begin > beginning, permit > permitting
Consonants = b, c, d, f, g, h, j, k, l, m, n, p, q, r, s, t, v, w, x, y, z
Vowels = a, e, i, o, u
Practice two-syllable ed-ing endings...
Rule 2: Words ending in E
ED = If the word ends in E, simply add D
ING = If the word ends in E, drop the E, add ING
Examples:
ED = smile > smiled, fine > fined
ING = dance > dancing, skate > skating
Rule 3: Words ending in Y
Consonant + Y
ED = If the word ends in Y, and has a consonant before it, change the Y to I and add ED.
ING = If the word ends in Y, and has a consonant before it, simply add ING.
Examples:
ED = study > studied, marry > married
ING = carry > carrying, reply > replying
Vowel + Y
ED = If the word ends in Y, and has a vowel before it, simply add ED.
ING = If the word ends in Y, and has a vowel before it, simply add ING.
Examples:
ED = play > played, stay > stayed
ING = enjoy > enjoying, stray > straying
Rule 4: Other words...
words ending in two vowels + a consonant
ED = If the word ends in two vowels + a consonant, simply add ED.
ING = If the word ends in two vowels + a consonant, simply add ING.

Examples:
ED = dream > dreamed, rain > rained
ING = need > needing, beep > beeping
words ending in a double consonant:
ED = If the word ends in a double consonant, simply add ED.
ING = If the word ends in a double consonant, simply add ING.
Examples:
ED = park > parked, earn > earned
ING = need > needing, laugh > laughing

重读闭音节结尾的词才要双写，也就是末尾是“辅音+元音+辅音”的音节，重音还必须在这个音节上。

1.直接加ing do---doing2.以不发音的e结尾的,去e加ing dance--dancing3.以重读闭音节,而且末尾只有一个辅音字母结尾的,双写这个辅音字母,再加ing.get--gettingbegin--beginninghappen不是重读闭音节,重读是ha.很高兴...