Lack of security of tenure was a reason for many families becoming homeless.是什么意思？

Lack of security of tenure was a reason for many families becoming homeless.

居住权得不到保证是许多家庭居无定所的一个原因。

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。

security

n. 安全，保证，担保，保护，防护，有价证券；adj. 安全的，保安的，保密的；

例句
You've illegally accessed and misused confidential security files.
你已经非法访问并盗用了机密的安全文件。

tenure

n. 占有（职位，不动产等），占有期，终身职位；

例句
Lack of security of tenure was a reason for many families becoming homeless.
居住权得不到保证是许多家庭居无定所的一个原因。

was

v. 用来表示某人或某物即主语本身，用来表示某人或某物属于某一群体或有某种性质（ be的过去式 ），在，存在，不受干扰；

例句
There was a terrible sadness in her eyes...
她眼神中流露出深深的悲伤。

reason

n. 理由，原因，理性，理智；vt.& vi. 推理，思考，争辩，辩论，向…解释；

例句
As always, Peter had a reason for his action...
一如往常，彼得对自己的行为总有说辞。

for

prep. 为，为了，倾向于，关于，当作；conj. 因为，由于；

例句
I've come looking for a bit of advice.
我特来讨教。

many

adj. 许多，多的；pron. （与复数动词连用）大多数人；

例句
There are many people who still find the act of abortion abhorrent.
仍有很多人对堕胎行为表示厌恶。

families

n. 家( family的名词复数 )，家族，（大）家庭（包括父母子女及近亲），语族；

例句
We have been working very hard, and our families have also worked hard...
我们一直很努力工作，并且我们的家人也是如此。

becoming

adj. <正>（衣服等）相配的，合身的，合适的，与…相称的；n. <哲>（变化过程的）形成，发生；v. 变为，成为( become的现在分词 )，适合，使（人）显得漂亮，使好看；

例句
He had discovered politics and was rapidly becoming absorbed by it...
他接触到了政治并且迅速地对它着了迷。

homeless

adj. 无家可归的，露宿风餐；

例句
For me to think I'm any better than a homeless person on the street is ridiculous.
在我看来，认为我自己比街上的无家可归者要更加高尚是很可笑的。