e

• 英语字母表中的第五个字母，是元音。它是英语中最常用的字母，可以表示多种不同的读音，也常用作音乐音名、不及格成绩、数学常数或电子格式的标志。

The fifth letter of the English alphabet and the second vowel, representing several sounds including the long /iː/ as in 'he', the short /ɛ/ as in 'bed', and the schwa /ə/ as in 'taken'. As the most frequently used letter in the English language, 'E' appears in approximately 11% of all written English text. It functions as a musical note, an academic grade indicating failure or conditional status, a mathematical constant representing Euler's number, and a designation in electronic and digital contexts.

1. The fifth letter of the English alphabetA1formal

   The uppercase or lowercase character (E, e) that constitutes the fifth symbol in the Latin-based English alphabet, classified as a vowel. It is the most frequently occurring letter in written English, accounting for roughly 11% of all characters in typical text. Its pronunciation varies widely, representing long /iː/, short /ɛ/, schwa /ə/, or remaining silent in many words, making it one of the most phonologically complex letters.

   英文字母的第五个字母

   • The letter E is the most common letter in English words.
   • In the word 'bed', the E makes a short vowel sound.
   • The silent E at the end of 'hope' changes the pronunciation of the O.
   • She wrote her name with a capital E at the beginning.
   • Cryptographers know that E is the most frequent letter in substitution ciphers.

2. The musical note EB1formalart

   The third note in the diatonic scale of C major, positioned two whole steps above the tonic C. In fixed-do solfège it is called 'mi'. It is a crucial reference pitch for string instruments: the highest string on a violin and the lowest string on a standard-tuned guitar are both tuned to E. The key of E minor is one of the most commonly used keys in rock and guitar-based music.

   E音

   • The guitarist played an E minor chord to begin the song.
   • The violin's E string produces the instrument's highest pitch.
   • The piece is written in E major, which has four sharps.
   • She tuned the lowest guitar string to drop E for a heavier sound.
   • The melody prominently features the note E above middle C.

3. A failing or conditional academic gradeB2formal

   A letter symbol used in some educational grading systems, with meanings that vary by institution. In many systems using A through F, it denotes failure when below D. However, in some schools that skip E to avoid confusion with 'Excellent', an E grade may represent a conditional pass or a specific sub-standard. In certain international systems, E can signify the lowest passing or highest failing mark.

   不及格或条件性学业成绩

   • In my old school, an E was considered a failure requiring course repetition.
   • The report card showed an E in mathematics, shocking his parents.
   • Some UK universities use E as a marginal fail grade.
   • She received an E in conduct for her behavior that semester.
   • The grading scale went from A to E, with E being barely acceptable.

4. Euler's number, the mathematical constantC1formalscientific

   A fundamental mathematical constant approximately equal to 2.71828, serving as the base of the natural logarithm. Named after the Swiss mathematician Leonhard Euler, it is an irrational and transcendental number that appears naturally in contexts involving continuous growth, compound interest, calculus, and complex analysis. The exponential function e^x is unique in being its own derivative.

   欧拉数，数学常数

   • The value of e to five decimal places is approximately 2.71828.
   • Natural logarithms use e as their base rather than 10.
   • The formula for continuous compound interest involves e raised to the rt power.
   • Euler's identity elegantly links e, pi, i, 1, and 0.
   • The derivative of the function e^x is simply e^x itself.

5. A designation for electronic or digital formatsA2formalIT

   A prefix or initial used to denote 'electronic' in compound terms, signifying digital, online, or electronically mediated versions of traditionally physical activities or products. It commonly appears as 'e-' in words like e-mail, e-commerce, e-book, and e-learning, reflecting the digitization of communication, commerce, literature, and education in the internet age.

   电子或数字格式的标识

   • She prefers reading e-books on her tablet rather than physical copies.
   • The rise of e-commerce has transformed the retail industry worldwide.
   • I received an e-ticket for the concert instead of a paper one.
   • Many universities now offer e-learning platforms for remote students.
   • The company's e-wallet app supports multiple currencies.