r是什么意思

2023-12-20 17:45:16

美[ɑːr] 英[ɑː(r)]

n. 字母r

名词复数：rs

近义词：radius，universalgasconstant，gasconstant，roentgen，

n.(名词)

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。