A /e/ 名詞
 英文字母的第一個字母, 第一


 a /ə; e/ 冠詞
 /ə/ 輕讀
 /e/ 重讀
 一個, 每一, 同一 (用於未曾提及或事先不知的名詞前，名詞以子音起音)


 A
 A暫存器(同register,arithmetic)


 A
 1.  An adjective, commonly called the indefinite article, and signifying one or any, but less emphatically. “At a birth”; “In a word”; “At a blow”. --Shak.
 Note: It is placed before nouns of the singular number denoting an individual object, or a quality individualized, before collective nouns, and also before plural nouns when the adjective few or the phrase great many or good many is interposed; as, a dog, a house, a man; a color; a sweetness; a hundred, a fleet, a regiment; a few persons, a great many days.  It is used for an, for the sake of euphony, before words beginning with a consonant sound [for exception of certain words beginning with h, see An]; as, a table, a woman, a year, a unit, a eulogy, a ewe, a oneness, such a one, etc.  Formally an was used both before vowels and consonants.
 2.  In each; to or for each; as, “twenty leagues a day”, “a hundred pounds a year”, “a dollar a yard”, etc.


 A prep.
 1. In; on; at; by.  [Obs.] “A God's name.”  “Torn a pieces.” “Stand a tiptoe.” “A Sundays” --Shak. “Wit that men have now a days.” --Chaucer. “Set them a work.” --Robynson (More's Utopia).
 2. In process of; in the act of; into; to; -- used with verbal substantives in -ing which begin with a consonant. This is a shortened form of the preposition an (which was used before the vowel sound); as in a hunting, a building, a begging. “Jacob, when he was a dying” --Heb. xi. 21.  “We'll a birding together.” “ It was a doing.” --Shak.  “He burst out a laughing.” --Macaulay.
 Note: The hyphen may be used to connect a with the verbal substantive (as, a-hunting, a-building) or the words may be written separately. This form of expression is now for the most part obsolete, the a being omitted and the verbal substantive treated as a participle.


 A.  Of.  [Obs.] “The name of John a Gaunt.”  “What time a day is it ?” --Shak. “It's six a clock.” --B. Jonson.


 A. A barbarous corruption of have, of he, and sometimes of it and of they.  “So would I a done” “A brushes his hat.”


 A. An expletive, void of sense, to fill up the meter
 A merry heart goes all the day,
 Your sad tires in a mile-a.   --Shak.

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 A The first letter of the English and of many other alphabets. The capital A of the alphabets of Middle and Western Europe, as also the small letter (a), besides the forms in Italic, black letter, etc., are all descended from the old Latin A, which was borrowed from the Greek Alpha, of the same form; and this was made from the first letter (░) of the Phœnician alphabet, the equivalent of the Hebrew Aleph, and itself from the Egyptian origin. The Aleph was a consonant letter, with a guttural breath sound that was not an element of Greek articulation; and the Greeks took it to represent their vowel Alpha with the ä sound, the Phœnician alphabet having no vowel symbols.
 This letter, in English, is used for several different vowel sounds. See Guide to pronunciation, §§ 43-74. The regular long a, as in fate, etc., is a comparatively modern sound, and has taken the place of what, till about the early part of the 17th century, was a sound of the quality of ä (as in far).
 2. Mus. The name of the sixth tone in the model major scale (that in C), or the first tone of the minor scale, which is named after it the scale in A minor. The second string of the violin is tuned to the A in the treble staff. -- A sharp (A♯) is the name of a musical tone intermediate between A and B. -- A flat (A♭) is the name of a tone intermediate between A and G.
 A per se , one preëminent; a nonesuch. [Obs.]
 O fair Creseide, the flower and A per se
 Of Troy and Greece.   --Chaucer.


 A
      n 1: the blood group whose red cells carry the A antigen [syn: {type
           A, group A]
      2: a metric unit of length equal to one ten billionth of a
         meter (or 0.0001 micron); used to specify wavelengths of
         electromagnetic radiation [syn: angstrom, angstrom unit]
      3: any of several fat-soluble vitamins essential for normal
         vision; prevents night blindness or inflammation or
         dryness of the eyes [syn: vitamin A, {antiophthalmic
         factor, axerophthol]
      4: one of the four nucleotides used in building DNA; all four
         nucleotides have a common phosphate group and a sugar
         (ribose) [syn: deoxyadenosine monophosphate]
      5: (biochemistry) purine base found in DNA and RNA; pairs with
         thymine in DNA and with uracil in RNA [syn: adenine]
      6: the basic unit of electric current adopted under the Systeme
         International d'Unites; "a typical household circuit
         carries 15 to 50 amps" [syn: ampere, amp]
      7: the 1st letter of the Roman alphabet


 A
    Alpha, the first letter of the Greek alphabet, as Omega is the
    last. These letters occur in the text of Rev. 1:8,11; 21:6;
    22:13, and are represented by "Alpha" and "Omega" respectively
    (omitted in R.V., 1:11). They mean "the first and last." (Comp.
    Heb. 12:2; Isa. 41:4; 44:6; Rev. 1:11,17; 2:8.) In the symbols
    of the early Christian Church these two letters are frequently
    combined with the cross or with Christ's monogram to denote his
    divinity.