1. the youth是个复数形式，表示青年男女的整体，如police, people类似。如：
The youth of the country are ready for fight.
这个国家的青年都准备好去战斗。
The youth of the country are being ignored by their leaders.
该国的青年没有受到领导人的重视。
The youth fully displayed their courage and skill in the football field.
小伙子们在绿茵场上大显身手。
She's not a very good influence on the youth of this country.
她对这个国家的青年一代没什么好影响。
The youth of our country are often compared to the rising sun.
我国的青年常被比作初升的太阳。
He represents the opinions of the youth of today...
他代表着当今年轻人的看法。
The singer is regarded as a representative of the youth of her generation.
这位歌手被看作是她那一代年轻人的典型代表。
当然，the youth也可以表示：那个青年人，那个年轻人，那个小伙子
The youth was charged with three counts of burglary.
那位年轻人被控犯有三次盗窃罪。
The youth continued to gawk at her and did not answer.
那个年轻人依然傻乎乎地望着她，没有答话。
The youth got him by the front of his shirt and flung him to the ground.
年轻人抓住他的衬衫前襟，把他摔在了地上。
2.the youth那个年轻人，那个年青人，那个小伙子
a youth 一个年青人
six youths六个年轻人
当指一个一个的年轻人的个体时，youth普通的可数名词。
As a youth he discovered a gift for teaching
他年轻时就表现出教书的天赋。
There are groups of youths playing basketball over there.
成群的小伙子正在那里打篮球。
There was a group of youths standing on the street corner.
有一群年轻人站在街角。
Drunken youths hang around outside looking for trouble.
喝醉的年轻人在街头游荡滋事。
Youths had broken into the bar and smashed the place up.
一群年轻人闯进酒吧，把里面砸了个乱七八糟。
The fight was started by a gang of youths.
这场打斗是一伙少年挑起来的。
Gangs of youths went on the rampage in the city yesterday.
成群结伙的年轻人昨天在城里横冲直撞。
Gangs of youths patrol the streets at night.
夜里成帮结伙的年轻人在街上闲逛。