lack的意思：
vt. 缺乏，缺少；需要的東西；
n. 缺乏，不足，沒有；缺少的東西；
lack的用法：
一、lack用作名詞 表示 “不足”。 通常用 “lack+of＋名詞”。
①A deficiency or an absence: 缺乏或沒有；
②Something needed or wanted. 欠缺的事物：缺乏或尋求的某物
a lack of money. 缺乏金錢
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. 沒有食物，他再也堅持不下去了。
二、lack用作及物動詞表示 缺乏；不足；沒有
①To be entirely without or have very little of.缺乏：根本就沒有或僅有一點
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. （與孩子打交道她缺少耐心。）
We are lacking three members of staff due to illness.(注：說lack不用于進行時是站不住腳的)
三、lack用作不及物動詞 還可作“缺乏，短少；不足；需要。常用進行時
①To be wanting or deficient:缺乏：處于匱乏或不足狀態：
You will not be lacking in support from me.你將得到我的幫助
（注：這里把lacking處理為vi.，并沒有作為adj.來得簡單）
②To be in need of something:需要：需要某物：
I lacked for nothing.我不需要任何東西
She does not lack for friends.
They lacked for nothing.他們無所需求（應有盡有）。