vt. 缺乏，缺少；需要的东西；
n. 缺乏，不足，没有；缺少的东西；
一、lack用作名词 表示 “不足”。 通常用 “lack+of＋名词”。
①A deficiency or an absence: 缺乏或没有；
②Something needed or wanted. 欠缺的事物：缺乏或寻求的某物
a lack of money. 缺乏金钱
Her only problem is lack of confidence. Lack of sleep had made him irritable. If he fails it won't be for/through lack of effort (= he has certainly tried). We won't be going on holiday this year - lack of funds, I'm afraid. He can’t endure the lack of food. 没有食物，他再也坚持不下去了。
二、lack用作及物动词表示 缺乏；不足；没有
①To be entirely without or have very little of.缺乏：根本就没有或仅有一点
②To be in need of.需要
He just lacks a little confidence. What we lack in this house is space to store things. She lacks patience in dealing with children. （与孩子打交道她缺少耐心。）
We are lacking three members of staff due to illness. (注：说lack不用于进行时是站不住脚的)
三、lack用作不及物动词 还可作“缺乏，短少；不足；需要。常用进行时
①To be wanting or deficient:缺乏：处于匮乏或不足状态：
You will not be lacking in support from me.你将得到我的帮助
（注：这里把lacking处理为vi.，并没有作为adj.来得简单）
②To be in need of something:需要：需要某物：
I lacked for nothing.我不需要任何东西
She does not lack for friends.
They lacked for nothing.他们无所需求（应有尽有）。
be lacking:欠缺、缺：
be lacking in缺乏（某种品质、特点等）,不够
lack for 缺（多用于否定句）
Lack+of＋名词： The plants died for lack of water.
Lack+名词： We lack the strength to walk any further.
短语：
be lacking:欠缺、缺： Money was lacking to complete the building.
Be lacking in缺乏（某种品质、特点等）,不够： He is not lacking in intelligence.
Lack for 缺（多用于否定句） She does not lack for friends
1. Lack of exercise can lead to feelings of depression and exhaustion.
缺乏锻炼会导致抑郁和疲劳。
2. Despite his lack of experience, he got the job.
他虽然经验不足，但还是获得了这份工作。
3. There's a lack of fussiness about the way he works.
他工作时不会过分注重细节。
4. She wrinkled her nose, piqued by his total lack of enthusiasm.
她皱皱鼻子，为他毫无热情而感到不快。
5. There's always a lack of consistency in matters of foreign policy.
外交政策总是缺乏连贯性。
6. Despite its lack of formal power the nobility was not powerless.
尽管没有正式的权力，贵族阶层并非没有权势。