They were exhausted from lack of sleep...是什么意思？

They were exhausted from lack of sleep...

由于缺乏睡眠，他们非常疲惫。

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。

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。

exhausted

adj. 耗尽的，用完的，筋疲力尽的，精疲力竭的；v. 用尽( exhaust的过去式和过去分词 )，使非常疲倦，详尽讨论（或研究），弄空；

例句
She arrived home exhausted and barely capable of showering before collapsing on her bed.
她精疲力竭地回到家，勉强冲了个澡就倒在了床上。

from

prep. （表示时间）从…，（表示原因）因为，（表示来源）来自…，（表示分离）与…分离[隔开]；

例句
...an abortive attempt to prevent the current President from taking office.
企图阻止现任总统连任的失败尝试

lack

vt. 缺乏，缺少，需要的东西；n. 缺乏，不足，没有，缺少的东西；

例句
Stress and lack of sleep can aggravate the situation...
压力和睡眠不足会使情况恶化。

of

prep. 关于，属于…的，由…制成；aux. 助动词 [非标准用语、方言] =have [主用于虚拟语气]；

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

sleep

vi.& link-v. 睡，睡觉；vi. 睡，睡觉，睡眠状态；vt. 为…提供床位，提供住宿，以睡觉打发日子；n. 睡眠；

例句
Their sleep is regularly disturbed by the sound of gunfire as criminal gangs settle their nightly accounts.
他们经常被黑帮每晚火拼的枪声所吵醒。