Hm, It seems I am unable to edit my previous posts
1.1. The AlphabetNumerically speaking, the standard modern Vietnamese alphabet consists of 12 vowels (y is considered a vowel) and all English consonants except for f, j, w and z with the addition of đ and the digraphs ch, gi, kh, ng, nh, ph, qu, th and tr for a total of 25 consonants – 37 letters in total.
a ă â e ê i o ô ơ u ư y
b c(*1) ch d đ g(*2) gi h (k) kh l m n ng(*3) nh p ph qu r s t th tr v xNB: For orthographic reasons, (*1) is replaced by k preceding e, ê, i and y. Similarly, (*2) and (*3) are replaced by gh and ngh respectively for the same situation.1.2. InitialsEach of the 37 letters can act as an initial.
1.3. FinalsThe letters which cannot be finals are: ă, â and every consonant except for ch, m, n, ng, nh, p and t.
1.4. Diphthongs and TriphthongsA > ai, ao, au, ay
 > âu, ây
E > eo
Ê > êu
I > ia (*1), iê, iêu (*2), iu
O > oa, oai, oe, oeo, oi
Ô > ôi
Ơ > ơi
U > ua(*3), uâ, uê, ui, uôi, uơ, uy, uya(*4), uyê, uyu
Ư > ưa (*5), ưi, ươ, ươi, ươu, ưu,
Y > yêu
NB: Again for orthographic reasons, (*1, 3, 4 and 5) are replaced respectively with iê, uô, uyê and ươ when they are not finals. (*2) is replaced by yêu when the triphthong is by itself. Example 1/So now that we know the alphabet, let’s have a look at how they build up! (Of course, not all combinations are used). Let’s take kh as the initial and see how many possible combinations with vowels or diph-/triphthongs we can make.
A > kha, khai, khao, khau, khay
 > khâu, khây
E > kheo
Ê > khêu
I > khia, khiê-, khiêu, khiu
O > khoa, khoai, khoe, khoeo, khoi
Ô > khôi
Ơ > khơi
U > khua, khuâ-, khuê, khui, khuôi, khuơ, khuy, khuya, khuyê-, khuyu
Ư > khưa, khưi, khươ-, khươi, khươu, khưu
Example 2/Examples of where c, g and ng assume their alternate forms.
Ca, co, cư > kê, ki
Ga, go, gư > ghê, ghi
Nga, ngo, ngư > nghê, nghi
Example 3/Some examples of those vowels and diph-/triphthongs which have alternate spellings.
Kia > kiên
Cua > cuôn
Cưa > cươn
Kiêu - yêu