d

• 英文字母表的第四个字母，为辅音。表示浊齿龈塞音/d/。常用作低分、音符、罗马数字500、第四类或劣质等级的符号。

The fourth letter of the English alphabet and the third consonant, representing the voiced alveolar plosive sound /d/. As a grapheme, 'D' is produced by pressing the tongue against the alveolar ridge and releasing it with vocal cord vibration. It appears frequently as a regular past-tense verb ending marker. It functions as a barely passing academic grade, a musical note, a Roman numeral for 500, and a designation for the fourth category or class in hierarchical systems.

1. The fourth letter of the English alphabetA1formal

   The uppercase or lowercase character (D, d) that constitutes the fourth symbol in the Latin-based English alphabet, classified as a consonant. It represents a voiced plosive sound produced by the tongue making contact with the alveolar ridge just behind the upper front teeth. It is also a crucial marker for forming the regular past tense and past participle of many English verbs.

   英语字母表的第四个字母

   • The word 'dog' begins with the letter D.
   • Add the letter d to 'play' to make it past tense.
   • The child wrote a big capital D followed by a lowercase d.
   • In alphabetical order, D comes after C and before E.
   • He has difficulty pronouncing the d sound at the end of words.

2. A poor but barely passing academic gradeB1formalamerican

   A letter symbol used in educational grading systems to denote marginal or below-average performance, typically corresponding to a numerical score range of 60-69%. It represents the lowest passing grade in many institutions, indicating genuine effort but insufficient mastery of the subject matter. A D is often considered unacceptable for major-specific courses requiring at least a C.

   勉强及格的成绩

   • He barely passed the course with a D-minus.
   • A D grade may not count toward your major requirements.
   • She was disappointed to receive a D on the final exam.
   • Getting a D is better than failing with an F, but not by much.
   • The professor advised him to retake the class if he got a D.

3. The musical note DB1formalart

   The second note in the diatonic scale of C major, positioned one whole step above the tonic C. In fixed-do solfège it is called 're'. It is a fundamental tone in string instrument tuning, as the violin's second-highest string and the cello's second-highest string are both tuned to D. The key of D major, with two sharps, is one of the most commonly used keys for guitar and orchestral music.

   音符D

   • The violin's D string produced a warm, resonant tone.
   • Pachelbel's Canon is famously written in the key of D major.
   • She tuned her guitar to drop D for the heavy riff.
   • The melody ascends from middle C to the D above it.
   • Trumpets in D were common in Baroque orchestral music.

4. The Roman numeral for 500B1formal

   The symbol D used in the Roman numeral system to represent the cardinal number five hundred (quingenti in Latin). Its origin may derive from half of the symbol CIƆ, which represented 1000. It appears in historical dates, monument inscriptions, and formal numbering of significant events, though less frequently than C and M.

   罗马数字500

   • The year 1500 in Roman numerals is written as MD.
   • The ancient arch was inscribed with the number DL, meaning 550.
   • Roman legion sizes were often multiples of D, or 500 soldiers.
   • The manuscript dates back to anno Domini MDC, or 1600.
   • The monument commemorates D years since the city's founding.

5. The fourth category, class, or grade in a seriesB2informal

   A designation used to mark the position, item, or category that follows C in an ordered sequence, often implying the lowest or least desirable tier in a ranking system. It can denote inferior quality, lower priority, or the last acceptable option in classifications, such as D-list celebrities, vitamin D classification as a fat-soluble nutrient, or the fourth tier in pricing schemes.

   第四类，第四等

   • He was relegated to the D-team after poor performance in the tryouts.
   • D-list celebrities rarely get invited to major award shows.
   • The insurance plan only covers Category D medications at 50%.
   • Their seats in the nosebleed section were clearly in Row D.
   • Vitamin D is essential for calcium absorption and bone health.