1.generation的意思是“同时代的人,一代,一代人”,为可数名词,可用于复数形式,也可加不定冠词a修饰。
2.generation还有“产生,发生,繁殖(后代)”的意思,主要指发电,产生热等,这时是不可数名词。

a generation ago
约三十年以前; 一代人以前 about 30 years ago; before a period of time in which a human being can grow up and have a family
This happened a generation ago.这件事发生在30年前。
“Two generations ago” means the time your grandfather was your age.“两代人以前”指的就是你祖父像你这么大的时候。

for generations
一连好几代,几代相传 long time
These diamonds have been handed down in his family for generations.这些钻石在他家已经传了好几代。
This heirloom has been handed for several generations.此项产业已经数代相传了。

from generation to generation
世世代代,一代代 for generations
This book was handed down from generation to generation.这本书世代相传。

generation gap
代沟 difference in attitude, or lack of understanding, between young people and older people
Do you want to bridge the generation gap?你想弥合代沟吗?
In a day when the generation gap yawns ever wider parents and children have become strangers to one another.某一天代沟的裂缝变得更宽时,父母和孩子之间会相互变成陌生人。
How can teachers help to bridge the generation gap between parents and their teenage children?教师怎样才能帮助弥补父母与青少年之间的代沟呢?

The younger generation is avid of new experiences.年轻一代热望新奇的经历。
In Britain, and probably many other countries too, teachers and parents are worried about this generation of school-children.在英国,也许还有许多别的国家,教师和家长都为这一代的小学生担心。
Lu Hsun had influenced more than one generation of the Chinese people.鲁迅影响了不止一代的中国人。
People of my generation all think the same way about this.关于这件事,我们这代人都有同感。
China is building up a new generation of scientists.中国正在造就新一代科学家。
The latest generation of anti-tank missiles has several new refinements.最新一代的反坦克导弹有几种新的改进装置。
Three generations of the family have been born and brought up in this old house.这个家族的三代人都是在这所古老的房子里出生和成长的。
The tradition is handed down the generations.传统代代相传下来。
Steam and water power are used for the generation of electricity.蒸汽和水力可用来发电。
The biology class studied the generation of fruit flies.生物班的学生研究了果蝇的繁殖。

generation, age, period
参见period条。

［同义词］   age, breed, period, time