lack的意思：
vt. 缺乏，缺少；需要的东西；
n. 缺乏，不足，没有；缺少的东西；
lack的用法：
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）。