A

/ei, ə/
Học thuật
Thân thiện
Definition

  1. Indefinite Article:

    • Used before singular nouns to refer to a non-specific person or thing for the first time, or to indicate one single member of a class. It is used before consonant sounds.
    • Example: I saw a dog. (This introduces a dog that has not been mentioned before.)

  2. Noun:

    • The first letter of the English and Roman alphabet.
    • A grade or score indicating the highest level of quality.
    • In music, the sixth note of the diatonic scale of C major.
Usage Examples

  • Indefinite Article:

    • She is a doctor. (She belongs to the class of people who are doctors.)
    • I need a pen. (Any single, non-specific pen.)
    • He earns fifty dollars a day. (Per day.)

  • Noun:

    • The word "apple" starts with an 'a'. (Referring to the letter.)
    • He got an A on his test. (Referring to the top grade.)
    • The orchestra tuned to the note A. (Referring to the musical pitch.)
Advanced Usage

  • "A" as a prefix: Can mean "not" or "without" in words of Greek origin.

    • Atypical means not typical.
    • Amoral means not concerned with morality.

  • "From A to Z": Covering everything completely; from beginning to end.

    • She knows the subject from A to Z.

  • "A-1" or "A-one": Of the best quality; first-rate.

    • The service at the hotel was A-1.
Variants and Related Words
  • An: The form of the indefinite article used before vowel sounds (e.g., , ).
  • A-: A prefix, as in , meaning not social.
Synonyms
  • One (when used to indicate a single item).
  • Any (when used to indicate a non-specific item).
  • Per (when used in expressions of rate).
Related Phrases (Phrasal Verbs)
  • Not know A from B: To be completely ignorant.
    • He doesn't know A from B when it comes to fixing cars.
Related Idioms
  • An A for effort: Recognition for trying hard, even if the result isn't perfect.
    • Your project had problems, but I give you an A for effort.
Noun
  1. the blood group whose red cells carry the A antigen
  2. the 1st letter of the Roman alphabet
  3. the basic unit of electric current adopted under the Systeme International d'Unites
    • a typical household circuit carries 15 to 50 amps
  4. (biochemistry) purine base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA
  5. one of the four nucleotides used in building DNA; all four nucleotides have a common phosphate group and a sugar (ribose)
  6. any of several fat-soluble vitamins essential for normal vision; prevents night blindness or inflammation or dryness of the eyes
  7. a metric unit of length equal to one ten billionth of a meter (or 0.0001 micron); used to specify wavelengths of electromagnetic radiation

Từ đồng nghĩa

Từ gần giống

Từ chứa "A"

Từ có nhắc đến "A"