既然拉丁字母「U」是「V」派生出來的，為什麼「U」排在「V」前面？

12-30

謝謝邀請。

反對 @唐瓏珂的說法。英文維基直接說了：

V v : Latin letter V, from which U is directly descended
W w : Latin letter W, which, like U, is descended from V

U就是V的直系後代。

早期拉丁字母：

Archaic Latin alphabet[edit]
Old Italic alphabet
Letters

Transliteration
A
B
C
D
E
V
Z
H
Θ
I
K
L
M
N
Ξ
O
P
?
Q
R
S
T
Y
X
Φ
Ψ
F

Archaic Latin alphabet

As Old Italic

As Latin
A
B
C
D
E
F
Z
H
I
K
L
M
N
O
P
Q
R
S
T
V
X只有V沒有U。

中期也沒有U：

After the Roman conquest of Greece in the 1st century BC, Latin adopted the Greek letters ?Y? and ?Z? (or readopted, in the latter case) to write Greek loanwords, placing them at the end of the alphabet. An attempt by the emperor Claudius to introduce three additional letters did not last. Thus it was during the classical Latin period that the Latin alphabet contained 23 letters:

Classical Latin alphabet
Letter
ABCDEFGH
Latin name
á · ā
bé · bē
cé · cē
dé · dē
é · ē
ef · ef
gé · gē
há · hā
Latin pronunciation (IPA)
/a?/
/be?/
/ke?/
/de?/
/e?/
/?f/
/ɡe?/
/ha?/

Letter
IKLMNOPQ
Latin name
? · ī
ká · kā
el · el
em · em
en · en
ó · ō
pé · pē
qv? · qū
Latin pronunciation (IPA)
/i?/
/ka?/
/?l/
/em/
/?n/
/o?/
/pe?/
/ku?/

Letter
RSTVXYZ

Latin name
er · er
es · es
té · tē
vé · wē
ix · ix
? graeca · ī Graeca
zéta · zēta
Latin pronunciation (IPA)
/??/
/?s/
/te?/
/we?/
/iks/
/i? ?ɡrajka/
/?ze?ta/而當時還沒有W、U、J三個字母。

「De chalco graphiae inventio (1541, Mainz) with the 23 letters. W, U and J are missing.」

但也有認為U分化自Y的。

The letter u ultimately comes from the Semitic

[specify]

letter Waw by way of the letter y. See the letter y for details.

During the late Middle Ages,
two forms of "v" developed, which were both used for its ancestor "u"
and modern "v". The pointed form "v" was written at the beginning of a
word, while a rounded form "u" was used in the middle or end, regardless
of sound. So whereas "valor" and "excuse" appeared as in modern
printing, "have" and "upon" were printed "haue" and "vpon". The first
distinction between the letters "u" and "v" is recorded in a Gothic
alphabet from 1386, where "v" preceded "u". Printers eschewed capital
"U" into the 17th century and the distinction between the two letters
was not fully accepted by the French Academy until 1762.

[3]

而English alphabet說明，古英語也只有

A B C D E F G H I K L M N O P Q R S T V X Y Z ? ? T D ?

The letters u and j, as distinct from v and i, were introduced in the 16th century, and w
assumed the status of an independent letter, so that the English
alphabet is now considered to consist of the following 26 letters:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z仍然沒有說明為何U出現在V之前，但和題主說的一樣，U派生自V。暫時無法解答了。