名詞 r:

1. a unit of radiation exposure; the dose of ionizing radiation that will produce 1 electrostatic unit of electricity in 1 cc of dry air
   同義詞：roentgen
2. (physics) the universal constant in the gas equation: pressure times volume = R times temperature; equal to 8.3143 joules per kelvin per mole
   同義詞：gas constant, universal gas constant
3. the 18th letter of the Roman alphabet
   同義詞：letter r
4. the length of a line segment between the center and circumference of a circle or sphere
   同義詞：radius

1. The trilled `r' is produced by vibrating the tongue against the upper teeth.
   發(fā)帶顫音的r，舌抬向上齒顫動而成。

r 或 R

n.（名詞）
【復數(shù)】 r`s 或 R`s
The 8th letter of the modern English alphabet.
字母R：現(xiàn)代英語字母表中的第十八個字母
Any of the speech sounds represented by the letterr.
R的讀音：由字母r 所代表的讀音
The 8th in a series.
序列中的第十八

r
r 2
abbr.（略語）
Or R Mathematics Radius.
或 R 【數(shù)學】 Radius.
Or R Electricity Resistance.
或 R 【電學】 Resistance.
Or r. Baseball Run.
或 r. 【棒球】 Run.