The two policemen were joined by another policeman also carrying a pistol.是什么意思？

The two policemen were joined by another policeman also carrying a pistol.

另一名持枪警察和那两名警察会合了。

the

art. 指已提到的人（物），指说话人与听者已知的人（物），用于独一无二的事物前，与形容词最高级和序数词连用；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

two

n. 两个，两个东西，两点钟，一对；adj. 两个的，我

例句
He has been absent from his desk for two weeks...
他已经有两个星期没有坐在办公桌前了。

policemen

n. 警察，（男）警察( policeman的名词复数 )，捕役；

例句
Eight policemen then spent two years combing through the evidence.
之后8位警察花了两年时间搜寻证据。

were

be的过去时复数和第二人称单数形式，有时代替 was,用于条件从句、动词 wish 之后等；

例句
Shops, houses, and vehicles were set ablaze.
店铺、房子和车辆全都陷于火海。

joined

v. 连接( join的过去式和过去分词 )，联结，加入，参加；

例句
Podulski had joined the U.S. Navy as an aviator, adopting a new country and a new profession.
波度尔斯基加入美国海军当上了飞行员，不仅改了国籍还换了行当。

by

prep. 在…旁边，表示方式，由于，经过；adv. 经过，表示保留或保存时用，短暂拜访；

例句
...expensive make-up that we saw being advertised by a beautiful model...
我们所见的由一位漂亮模特代言的昂贵化妆品

another

adj. 又一个，再一个，另一的，其他一种；pron. 另一个，别个，再一个；

例句
He was accusing my mum of having an affair with another man...
他指责我妈妈与另一个男人有染。

policeman

n. （男）警察，警员，看守矿井的人，[化] 淀帚；

例句
A policeman has been shot dead in an ambush.
一次伏击中一名警察中弹身亡。

also

adv. 也，同样，并且；conj. 另外；

例句
The media have also abetted the feeling of unreality.
媒体也在一旁对这种非现实感推波助澜。

carrying

adj. 运送的，运输的；v. 支撑( carry的现在分词 )，携带，输送，运载；

例句
...regular flights carrying humanitarian aid to Cambodia...
向柬埔寨运送人道援助物资的定期航班

pistol

n. 手枪；v. 用手枪射击；

例句
...a starter pistol which only fires blanks.
只发射空包弹的发令枪