A, a
剑桥词典
A, a noun (LETTER)
[ 可数名词：有复数形式的名词 or 不可数或单数名词：没有复数形式的名词 ]the first letter of the English alphabet
（英语字母表的第一个字母）
A, a noun (MUSIC)
[ 可数名词：有复数形式的名词 or 不可数或单数名词：没有复数形式的名词 ]a note in Western music
A音
This concerto is in the key of A major . 这支协奏曲是 A 大调。
A, a noun (MARK)
[ 可数名词：有复数形式的名词 or 不可数或单数名词：没有复数形式的名词 ]a mark in an exam or for a piece of work that shows that your work is considered excellent
（学业成绩）A，优，甲
Sophie got an A for English . 苏菲英语得了个 A。
She got straight As (= all her marks were As) in her final exams . 她期末考试各科成绩均为 A。
Jim is a straight -A student (= all his marks are A). 吉姆是个全优生。
习语
from A to Bfrom A to Z 返回 A, a