• n. 字母A；第一流的；學業(yè)成績達最高標準的評價符號
• abbr. [物]安（ampere）

不定冠詞an在發(fā)展過程中出現(xiàn)的縮略形式，應用于首字母為輔音的單詞及h發(fā)音單詞。

a

a: [OE] The indefinite article in English is ultimately identical with the word one (as is the case, even more obviously, in other European languages – French un, German ein, and so on). The ancestor of both a(n) and one was ān, with a long vowel, but in the Old English period it was chiefly used for the numeral; where we would use a(n), the Anglo-Saxons tended not to use an article at all. ān begins to emerge as the indefinite article in the middle of the 12th century, and it was not long before, in that relatively unemphatic linguistic environment, its vowel became weakened and shortened, giving an.

And at about the same time the distinction between an and a began to develop, although this was a slow process; until 1300 an was still often used before consonants, and right up to 1600 and beyond it was common before all words beginning with h, such as house.
=> one

a (1)

indefinite article, mid-12c., a variation of Old English an (see an) in which the -n- began to disappear before consonants, a process mostly complete by mid-14c. The -n- also was retained before words beginning with a sounded -h- until c. 1600; it still is retained by many writers before unaccented syllables in h- or (e)u-, but is now no longer normally spoken as such. The -n- also lingered (especially in southern England dialect) before -w- and -y- through 15c.

a (2)

as in twice a day, etc., from Old English an "on," in this case "on each." The sense was extended from time to measure, price, place, etc. The habit of tacking a onto a gerund (as in a-hunting we will go) died out 18c.

1. Liver and kidney are particularly rich in vitamin A.

肝臟和腎臟富含維生素A。

來自柯林斯例句

2. Details are available from the Hon. Sec. A.R. Bushby.

詳情可咨詢名譽秘書A.R.布什比。

來自柯林斯例句

3. I was assigned to Troop A of the 10th Cavalry.

我被派往第10騎兵隊的A連。

來自柯林斯例句

4. Passes are graded from "A" down to "E".

及格分為A到E幾等。

來自柯林斯例句

5. Use only clean, Grade A, perfect eggs.

只用表面干凈、無磕碰的A級雞蛋。

來自柯林斯例句