lack, need, want, require

need(普通動詞), need(情態(tài)動詞)

• the pen needs mending.
  這支鋼筆需要修理。
• does she need to go to the club?
  她必須去俱樂部嗎？
• she does not need to go there at present.
  現(xiàn)在她不必去那里。

• need she go now?
  她必須現(xiàn)在去嗎？
• she need not come to school at present.
  她現(xiàn)在不必來學校。
• mary need not have done it.
  瑪麗本來不必去做那件事。（言外之意是：她已經做了）

名詞 need:

1. a condition requiring relief
   同義詞：demand
2. anything that is necessary but lacking
   同義詞：want
3. the psychological feature that arouses an organism to action toward a desired goal; the reason for the action; that which gives purpose and direction to behavior
   同義詞：motivation, motive
4. a state of extreme poverty or destitution
   同義詞：indigence, penury, pauperism, pauperization

動詞 need:

1. require as useful, just, or proper
   同義詞：necessitate, ask, postulate, require, take, involve, call for, demand
2. have need of
   同義詞：want, require
3. have or feel a need for

1. I feel a need to talk to you about it.
   我覺得有必要跟你談談那件事。
2. We are collecting money for children in need.
   我們在為貧困兒童募捐。
3. You needn't talk so loud.
   你說話的聲音用不著那么大。
4. The doctor told me I was in need of a good rest.
   醫(yī)生對我說，我需要好好休息。
5. If I need you to come and help I'll call.
   如果我需要你來幫忙，我會打電話的。

need

n.（名詞）
A lack of something required or desirable:
需要：對想要或期望的事物的缺乏：
例句：
crops in need of water; a need for affection.
需要水的莊稼；對感情的需要

Something required or wanted; a requisite:
必需品：要求或需要的事物；需要物：
例句：
Our needs are modest.
我們的必需品是謙虛

Necessity; obligation:
必要；義務：
例句：
There is no need for you to go.
你沒有必要去

A condition of poverty or misfortune:
貧困：貧窮或不幸的狀況：
例句：
The family is in dire need.
這個家庭極為貧困

v.（動詞）
need.ed,need.ing,needs
aux.（助詞）
To be under the necessity of or the obligation to:
必須要：必須要，有義務要：
例句：
They need not come.
他們不必來

v.tr.（及物動詞）
To have need of; require:
需要；想要：
例句：
The family needs money.
這個家庭需要錢

v.intr.（不及物動詞）
To be in need or want.
需要，想要
To be necessary.
有必要

來源：
Middle English nede
中古英語 nede
from Old English nôod, nôd [distress, necessity]
源自 古英語 nôod, nôd [窮困，貧困]

<參考詞匯><同義詞>need,necessity,exigency,requisiteThese nouns denote a condition in which something essential is required or wanted; they also refer to that which is required or wanted.
這些名詞都指處于對必需品的要求和需求的一種狀況；它們也指需要的或要求的東西。
Need is the most general:
Need 最普遍：
例句：
There`s no need to be concerned.
沒必要擔憂。

例句：
She is serene and contented;
她很安詳、平靜；

例句：
her emotional and spiritual needs are being met.
她感情和精神上的需要都得到了滿足。

Necessity more strongly thanneed suggests urgency, inevitability, or unavoidable obligation:
Necessity 比need 更強， 用來指緊迫的、不可避免的或不可躲避的義務：
例句：
.I think the necessity of being ready increases.—Look to it. (Abraham Lincoln).
.我認為做好準備的 緊迫性增加了。——注意. （亞伯拉罕·林肯）。

例句：
.The rehabilitation of the cabin became a necessity. (Bret Harte).
.小屋的重新修建已是不可避免的了. （布雷特·哈特）。

Exigency implies acute urgency,especially that arising from conditions or circumstances such as those of an emergency:
Exigency 指非常緊迫，尤指產生于類似緊急事件的條件或環(huán)境：
例句：
.No . . . more pernicious [doctrine] was ever invented . . . than that any of [the Constitution`s] provisions can be suspended during any of the great exigencies of government. (David Davis)
.沒有…曾經創(chuàng)造的 能比在一次政府的危急關頭對 條款的取消更為有害的. （大衛(wèi)·戴維斯）。

Requisite applies to something indispensable:
Requisite 指不可缺少的事物：
例句：
.a place where the three grand requisites of water, fuel and fodder were to be obtained. (James Fenimore Cooper).See also Synonyms at lack
.三種主要必需品，水、燃料和草料都具備的地方. （吉姆斯·費尼莫爾·庫珀）參見同義詞 lack

Depending on the sense,the verbneed behaves sometimes like an auxiliary verb (such as can or may ) and sometimes like a main verb (such aswant or try ). When used as a main verb,need agrees with its subject, takesto before the verb following it, and combines withdo in questions, negations, and certain other constructions:
根據(jù)語義，動詞need 有時當作助動詞來使用（如 can 或 may )， 有時象實義動詞（如want 或 try )。 當用作實義動詞時，need 和主語一致， 把to 放在其后面動詞的前面， 在疑問句、否定句或某些特定的造句法上和do 連用：
例句：
He needs to go.
他想走。

例句：
Does he need to go so soonô
他這么快就要走嗎ô

例句：
He doesn`t need to go.
他不需要走。

When used as an auxiliary verb,need does not agree with its subject, does not taketo before the verb following it, and does not combine withdo :
當用作助動詞時，need 不用和主語一致， 不用把to 放在其后動詞的前面， 并且不用和do 連用：
例句：
He needn`t go.
他不必走。

例句：
Need he go so soonô
他這么快就要走嗎ô

The auxiliary forms ofneed are used primarily in present-tense questions, negations, and conditional clauses. They differ subtly in meaning from the main verb forms in that they always refer to an externally imposed obligation.Hence one might sayYou needn`t (or less formally, don`t need to ) fill out both forms, but where the sense of necessity is internal to the subject,only the main verb can be used:
Need 的助動詞形式主要用于現(xiàn)在時態(tài)的疑問句、否定句和條件句中。 它們在意思上和用作實義動詞的形式有細微的區(qū)別，它們總指外部加強的壓力。因此我們可以說你沒必要 （或不太正規(guī)的 don`t need to ) 填兩份表格 ， 但是對于物體來說需要的意思是內在的，所以只能用實義動詞：
例句：
I don`t need to (not needn`t ) be told how to manage my own affairs.
我不需要（而不是 needn`t ) 被告訴怎知管理自己的事情 。

Note also that the use ofneed as an auxiliary is often accompanied by a presupposition that the activity in question has in fact been performed.The boys needn`t have spoken frankly implies that they did in fact speak frankly, whereas the sentenceThe boys did not need to speak frankly does not; only the latter could be followed by a clauselikethey conveyed their meanings by indirection.
還需注意need 用作助動詞時經常伴隨一個先決條件， 質問的動作事實上已經完成了。那些男孩們本來不需要坦誠相告的 意味著他們事實上已經坦率地說了， 然而這個句子男孩們不需要坦誠地說話 就沒有這個意思； 只有后者可以在其后跟這樣一個句子，如他們間接地表達他們的意思