i

• 英文字母表的第九个字母，是元音字母，可表示多种不同的读音。其独特之处在于，作为第一人称代词“我”时，在英语中始终大写。它也常被用作罗马数字1、物理学中电流的符号、序列中的第九项，或表示个人身份。

The ninth letter of the English alphabet and the third vowel, representing various sounds including the long /aɪ/ as in 'ice', the short /ɪ/ as in 'bit', and the long /iː/ as in 'machine'. As a grapheme, 'I' is unique for being the only single-letter English word that is always capitalized when used as the first-person singular pronoun. It functions as a Roman numeral for 1, a designation for the ninth item in a sequence, an academic grade in some systems, and an abbreviation for interstate highways, current, or intelligence.

1. The ninth letter of the English alphabetA1formal

   The uppercase or lowercase character (I, i) that constitutes the ninth symbol in the Latin-based English alphabet, classified as a vowel. It represents multiple phonemes: the long diphthong /aɪ/, the short monophthong /ɪ/, and the tense vowel /iː/ in loanwords. Typographically, the uppercase I and lowercase l can be easily confused in sans-serif fonts, as can the lowercase i and the numeral 1. A distinct feature of i is the dot, known as a tittle, which sits above the lowercase form.

   英文字母表的第九个字母

   • The word 'ice' begins with the long I sound.
   • In the word 'bit', the letter I makes a short vowel sound.
   • She dotted the lowercase i with a small heart.
   • The alphabet goes H, I, J after G.
   • Linguists distinguish between the tense and lax pronunciations of I.

2. The Roman numeral for 1A2formal

   The symbol I used in the Roman numeral system to represent the cardinal number one (unus in Latin). It serves as the fundamental building block for numbers up to three (I, II, III) and as a subtractive element combined with V and X to represent four and nine respectively. It is widely used in outlines, clock faces, chapter numbering, and formal designations of monarchs, popes, and sequential events.

   罗马数字1

   • King Henry VIII is read as King Henry the Eighth.
   • Chapter I of the book introduces the main characters.
   • The clock face uses I for one o'clock and II for two o'clock.
   • World War I began in 1914 and lasted until 1918.
   • Pope John Paul I served for only 33 days before his death.

3. A symbol for electric current in physicsB2formalscientific

   The uppercase letter I used as the standard notation for electric current in physics and electrical engineering, measured in amperes (amps). The symbol originates from the French phrase 'intensité du courant' (current intensity). It appears in fundamental equations such as Ohm's Law (V = I × R) and denotes the rate of flow of electric charge through a conductor, calculated as I = Q / t, where Q is charge and t is time.

   物理学中的电流符号

   • Ohm's Law states that V equals I times R.
   • The current I flowing through the circuit was measured at 5 amperes.
   • He calculated the electric current I using the formula I = Q / t.
   • The wire overheated because the current I exceeded its rated capacity.
   • Alternating current is represented as I(t) = I₀ sin(ωt).

4. An abbreviation for interstate highways in the USB1informalamerican

   The letter I used as a prefix in the United States to designate interstate highways, part of the Dwight D. Eisenhower National System of Interstate and Defense Highways. An I followed by a number (e.g., I-95, I-5, I-10) indicates a controlled-access highway that spans multiple states and is maintained by the federal government. Even-numbered interstates generally run east-west, while odd-numbered ones run north-south.

   美国州际公路

   • Take I-95 north to get from Miami to Washington, D.C.
   • Traffic on I-405 in Los Angeles is notorious for gridlock.
   • I-10 stretches from coast to coast across the southern United States.
   • The longest interstate is I-90, running from Seattle to Boston.
   • We stopped for gas at a rest area along I-75 in Georgia.

• 第一人称单数代词，说话人用来指称自己，在句中作主语。

The singular first-person subject pronoun in Modern English, used by the speaker or writer to refer to themselves as the subject of a verb.

1. First-person singular subject pronounA1formal

   Used as the subject of a verb when the speaker or writer is referring to themselves as the performer of an action or the topic of a statement.

   第一人称单数主格代词

   • I think I'd better go now.
   • When they asked me if I wanted the job, I said yes.
   • He and I are old friends.
   • I'm not going to fall, am I?
   • Jen and I went to London yesterday.