n.时期,学时,节,句点,周期,(妇女的)经期 adj.过去某段时期的 int.没有了
1 length or portion of time 一段时间; 时期
*a period of three years 三年的时间
* He has had several long periods of work abroad. 他在国外长期工作过几次.
* a period of peace, recovery, uncertainty 和平、恢复、不稳定时期
* showers and sunny periods, eg in a weather forecast 阵雨间晴（如在天气预报所述）
* The work must be completed within a two-month period. 工作须于两月内完成.
* The incubation period (ie The delay between catching a disease and the symptoms appearing) is two weeks. 该疾病的潜伏期为两星期.
2 (a) portion of time in the life of a person, nation or civilization （人、国家、文明的）时期, 时代
*a painting belonging to the artist's early period 该画家早期的画
* the period of the French Revolution 法国大革命时期
* the post-war period 战後时期
* The house is 18th century and has furniture of the period, ie of the same century. 那房子是18世纪的, 而且还有那时代的家具.
* The actors wore costumes of the period, ie of the time when the events of the play took place. 演员穿着剧中时代的服装.
* [usu attrib 通常作定语] period dress, furniture, etc 某时代的服装、家具等
* a period cottage, ie not modern 某时代的村舍.
(b) (geology 地质) portion of time in the development of the earth's surface 纪
*the Jurassic period 侏罗纪.
3 (time allowed for a) lesson in school （学校的）课, 课时, 学时
*a teaching period of
45 minutes 45分钟的一堂课
* a free period 没课的一节
* three periods of geography a week 每周三节地理课.
4 (a) monthly flow of blood from the womb of a woman; menstruation 月经
*have a period 来月经
* [attrib 作定语] period pains 月经痛.
(b) time of this 月经期.
5 (esp US)
(a) = full stop (full).
(b) sign of punctuation (.) marking this in writing and print 句号. =>App
(c) (infml 口) (added to the end of a statement to stress its completeness 加于一段话之後以强调完毕)
*We can't pay higher wages, period, ie that is final. 我们不能付再高的工资了, 话就说到这里.
6 (grammar) complete sentence, esp one having several clauses 完全句（尤指有几个分句者）.
7 (astronomy 天) time taken to complete one revolution 周期.
1. Can be achieved by a brief period lying, or even sitting down. 只要稍微躺一躺，甚至坐一坐就能达到。
2. But a closer study of the evidence, supported by a deeper sense of the period, and particularly by a new consciousness of the philosophical undercurrents in the scientific revolution, has profoundly modified this view of Galileo. 但是，对那个时代的深化了解，尤其是以科学家革命中哲学潜流的新意识为依据，进一步仔细研究，就会极大地改变对伽利略的看法。
3. But it was still too short a period for men to base a calendar on. 但时间依然太短，人们无法以此为据制定历法。
4. When research into cloning is resumed, human cloning should remain a research activity for an extended period. 当克隆研究重新开始时，克隆人类应该仍然是一项历时长久的研究活动。
5. The Qin dynasty existed for a very short period. 秦朝存在的时间很短。
6. The period following the Civil War said "Get set!"; 内战后的那段时期说"预备！
7. He could not have had a better mentor during this very trying period. 在这艰难的时刻他不可能找到比这位更好的老师了。
8. He was born in that turbulent period of history. 他出生在那个动荡的历史时期。
9. And another group were disturbed for an equal period of time but when they were not exhibiting eye-movements, 另一组人也是连续几夜被叫醒，但是在眼球队没活动时被叫醒的。
10. And a period (which is the time it takes a wave crest to travel one wave length). 和周期（海峰走过一个波长所需的时间）。