a

1.（用于可数名词或单数名词前，表示未曾提到的）一（人、事、物）used before countable or singular nouns referring to people or things that have not already been mentioned

2.（用于前有形容词或后有短语的不可数名词前）used before uncountable nouns when these have an adjective in front of them, or phrase following them

3.任何一；每一any; every

4.（表示为某一群体或职业中的一员）used to show that sb/sth is a member of a group or profession

5.（用于视为一体的两个名词之前）used in front of two nouns that are seen as a single unit

6.（用于某些数字前，代替 one）used instead ofone before some numbers

7.（用于价格、数量、比率等）一，每一used when talking about prices, quantities and rates

8.像（某人）的人；…式的人物a person like sb

9.（用于某人姓名前，表示说话者不认识此人）有个used before sb's name to show that the speaker does not know the person

10.（用于一星期中某天的名称前，表示具体某一天）used before the names of days of the week to talk about one particular day

1.英文字母表的第一字母

2.【数学】第一已知数

3.(学业成绩的)优等

4.表示“第一”的符号

5.腺苷

6.吸光率

1.〔普通可数名词第一次提到时,冠以不定冠词主要表示类别,有时则兼含“一”的概念〕

1.〔在数量概念上,说明表示时间,距离,重量及数目的名词〕一

2.〔与数量形容词,数词等连用而表示一个整体单位〕

3.〔与某些复数名词连用而仍表示一个单位〕

4.〔与序数词或形容词最高级结合共同限定所修饰的名词〕

5.〔表示同类事物中的代表〕任何一个[种]

6.同一的,相同的

7.一(副)

8.〔抽象名词用作普通名词,表示类别,例证〕

9.〔用于专有名词前,以整体概括个体,表示类似的一个或某一个〕

10.每(...),在...内,按(...而论),换(得)

11.〔口语〕一客

1.acceleration

2.activity

3.used to refer to the first vertical row of squares from the left on a chessboard

4.adenine

5.ampere

6.mass number

7.10

8.angstrom

9.used to indicate a main road other than a motorway

10.the first letter of the English alphabet, representing a vowel sound

11.a written representation of the letter "a"

12.the sixth note of a scale in C major. The A above middle C is often used to tune instruments and is standardized at a frequency of 440 hertz.

13.a string, key, or pipe tuned to produce the note A

14.a scale or key that starts on the note A

15.a graphic representation of the tone of A

16.the highest grade in a series, e.g. a top grade for academic work

17.a human blood type of the ABO system, containing the A antigen.

18.something shaped like a letter 'A'

19.in the market research system that classifies people according to their occupation, somebody in a senior management, professional, or administrative position

20.the sixth note in the musical scaleNDV> of C majorNDV>

21.a mark that a teacher gives to a student’s work to show that it is excellent

22.a common blood groupNDV> in the abo systemNDV>

1.used before a noun to indicate that somebody or something has some of the same qualities as the person or thing mentioned

2.used instead of "one" with words of measurement

3.in each or in every

4.used to indicate somebody not personally known, but known of

5.used in negative structures to emphasize a complete absence of something

1.used before a noun to indicate that somebody or something has some of the same qualities as the person or thing mentioned

2.used instead of 'one' with words of measurement

3.in each or in every

4.used to indicate somebody not personally known, but known of

5.used in negative structures to emphasize a complete absence of something

6.used when you are mentioning a person or a thing for the first time, or when the person listening to you does not already know about them

7.used when you mean any person or thing of a particular type, but you are not referring to a specific one

8.used when you say what class, type, or group someone or something belongs to, or what job someone has

9.used before a singular noun that represents every person or thing of a particular type

10.used when you are referring to a person or thing as one of several people or things of this type

11.used in expressions of quantity such as “a lot,” “a few,” or “a great deal”

12.used in numbers and measurements to mean “one,” as in “a thousand” or “an hour”

13.used in phrases showing how much something costs, how often it happens, how fast it goes, etc.

14.used before a noun that means a substance, product, food, etc. when referring to a particular type of it

15.used before the name of some drinks to mean a cup or glass of that drink

16.used before a noun that means a particular quality or feeling when the quality or feeling is described in some way

17.used before a noun that is formed from a verb and means a single action of that verb

18.used before a noun that expresses your feelings about a situation

19.used before the name of a particular day, season, or holiday to mean one particular Tuesday, summer, Christmas, etc.

20.used before a person’s name when you do not know anything about them

21.about

22.academy

23.acre

24.adult

25.answer

26.arrives

27.amp