They refused to negotiate unless three preliminary requirements were met.是什么意思？

They refused to negotiate unless three preliminary requirements were met.

如果三项先决条件得不到满足,他们就拒绝谈判.

they

pron. 他/她/它们，人们，大家，政府，当局，她们；

例句
The storms had abated by the time they rounded Cape Horn.
他们绕过合恩角时，暴风雨已经减弱。

refused

v. 拒绝，回绝( refuse的过去式和过去分词 )，推却，回绝，拒绝给（所需之物）；

例句
The army refused to accept orders from the political leadership...
军队拒绝接受政界领导层下达的命令。

to

prep. 向，朝着，到，关于，属于；adv. 朝一个方向的，到某种状态，关闭；

例句
I suggest you leave it to an expert...
我建议你把它留给专家来解决。

negotiate

vi. 谈判，协商，交涉；vt. 谈判达成，成功越过，议价出售；

例句
They recently failed to negotiate a mutually acceptable new contract.
他们最近未能谈成一个双方都满意的新合同。

unless

conj. 除非，如果不；prep. 除了，…除外；

例句
No-one can set up a waste disposal company unless they can show that they've got enough money and trained staff to do the job properly...
任何人若想成立废品处理公司,必须证明其拥有足够资金和受训员工以保证工作可以顺利开展。

three

num. 三，三个，第三（章，页等）；n. 三岁，三个人[东西]，三，三个；adj. 三的，三个的；

例句
Outsiders who wed islanders are given only three years' right of abode at first.
岛外的人和岛民结婚之初只能获得三年的居住权。

preliminary

adj. 初步的，初级的，预备的，开端的，序言的；n. 准备工作，预赛，初步措施，（对学生等的）预考；

例句
...a preliminary injunction enjoining the practice.
严禁那种做法的初步禁令

requirements

n. 所需的（或所要的）东西，必要条件，必备的条件，要求( requirement的名词复数 )，必要条件，需要，需要的东西；

例句
One of the most basic requirements for any form of angling is a sharp hook.
不管以什么方式钓鱼，有一个锋利的鱼钩都是最基本的要求之一。

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。

met

v. 相遇( meet的过去式和过去分词 )，相识，开会，接触（某物）；

例句
When I saw you across the room I knew I'd met you before.
我在房间那头看见你时就知道我曾见过你。