n. a period marked by distinctive character or reckoned from a fixed point or event
n. a major division of geological time; an era is usually divided into two or more periods
词态变化
复数形式:eras
常见例句
1
n a mathematical element that when added to another number yields the same number s indicating the absence of any or all units under consideration
2
n the smallest whole number or a numeral representing this number s used of a single unit or thing
3
n the cardinal number that is the sum of one and one or a numeral representing this number s being one more than one
4
Characterizing that kind of reasoning which derives propositions from the observation of facts, or by generalizations from facts arrives at principles and definitions, or infers causes from effects
