n. (名词)
- 英语字母中的第十八个字母（小写为r）
- 半径（radius）的符号
- 中世纪罗马数字的80
- R音
- R的活字
- 表示“第十八”的符号
- 伦琴射线，X射线（roentgen）的符号
- 卢布（ruble）
Noun:
-
a unit of radiation exposure; the dose of ionizing radiation that will produce 1 electrostatic unit of electricity in 1 cc of dry air
-
(physics) the universal constant in the gas equation: pressure times volume = R times temperature; equal to 8.3143 joules per kelvin per mole
-
the 18th letter of the Roman alphabet
-
the length of a line segment between the center and circumference of a circle or sphere
- The trilled `r' is produced by vibrating the tongue against the upper teeth.
发带颤音的r，舌抬向上齿颤动而成。
