either

詳細解釋：

ei.ther

pron.（代詞）
The one or the other:
任一，兩方，隨便哪一個：兩者中的一個或另一個：
例句：
Which movie do you want to seeô Either will be fine.
你想看哪一部電影ô哪部都行

conj.（連線詞）
Used before the first of two or more coordinates or clauses linked byor :
或…或…，…呢還是…，要么…要么…：用在以或 連線的兩個或多個並列成分或分句的第一個之前：
例句：
Either we go now or we remain here forever.
要么我們現在走，要么我們永遠在這呆下去

adj.（形容詞）
Any one of two; one or the other:
任一的：兩者之中任一的；一個或另一個：
例句：
Wear either coat.
穿隨便哪件衣服都行

One and the other; each:
兩方的，各自的：（兩者之中）一個和另一個；每個的：
例句：
rings on either hand.
兩隻手上的都戴著戒指

adv.（副詞）
Likewise; also. Used as an intensive following negative statements:
也：同樣；也。作為強調成分用在否定陳述之後：
例句：
If you don`t order a dessert, I won`t either.
如果你不點甜點，我也不點

來源：
Middle English
中古英文
from Old English ôther, ôghwôther * see k wo-
源自 古英文 ôther, ôghwôther *參見 k wo-

The traditional rule holds thateither should be used only to refer to one of two items and thatany is required when more than two items are involved:
傳統規則認為either 只能用於指兩者之一， 如果涉及多於兩者的情況時，套用any ：
例句：
Any (not either ) of the three opposition candidates still in the race would make a better president than the incumbent.
正在參加競選的三個 * 候選人中的任何 （不是 either ) 一個都會比現任總統幹得更好。

But reputable writers have often violated this rule,and in any case it applies only to the use ofeither as a pronoun or an adjective. Wheneither is used as a conjunction no paraphrase withany is available, and soeither is unexceptionable even when it applies to more than two clauses:
但是許多著名作家經常違反這個規則，這種情況只見於either 用作代名詞或形容詞時。 當either 用作連線詞時， any 沒有相應的替代詞， 所以即使用來連線多於兩個從句時，也要用either ：
例句：
Either the union will make a counteroffer or the original bid will be refused by the board or the deal will go ahead as scheduled. ·
或者工會提出一個相反的建議，或者董事會拒絕原來的要價，或者這事按原計畫進行。

Ineither . . . or constructions, the two conjunctions should be followed by parallel elements.The following is regarded as incorrect:You may either have the ring or the bracelet (properly, You may have either the ring or the bracelet ). The following is also incorrect:She can take either the examination offered to all applicants or ask for a personal interview (properly, She can either take . . . ). · When used as a pronoun,either is singular and takes a singular verb: The two left-wing parties disagree with each other more than either does (not do ) with the right. When followed byof and a plural noun, either is often used with a plural verb:
在either … or 結構中， 兩個連線詞後應跟並列成分。下面這句話被認為是不正確的：You may either have the ring or the bracelet ，正確的應是 You may have either the ring or the bracelet （你既可以有戒指也可以有手鐲） 下面這句也是不對的：She can take either the examination offered to all applicants or ask for a personal interview。 正確的應是， She can either take …（她可以參加提供給所有申請人的考試，也可以要求一個單獨面試。） 作為代名詞時，either 是單數，動詞套用單數形式： The two left-wing parties disagree with each other more than either does （不用 do ) with the right.（兩個左翼黨之間的分歧比任何一個與右翼黨的分歧都要大） 當後面接of 和一個複數名詞的時候， either 經常與動詞複數形式配合：
例句：
Either of the parties have enough support to form a government.
這些政黨中任一個都有足夠的支持來組閣一個政府。

But this usage is widely regarded as incorrect;in an earlier survey it was rejected by 92 percent of the Usage Panel. ·When all the elements in aneither . . . or construction (or a neither . . . nor construction) used as the subject of a sentence are singular, the verb is singular:
但是這種用法通常被認為是不正確的，在以前的調查中它被用法使用小組百分之九十二的成員所否定。當作為句中主語的either…or 結構（或 neither…nor 結構）中的所有成分都是單數的時候， 動詞也套用單數：
例句：
Either Eve or Herb has been invited.
伊夫和赫伯都被 邀請了。

Analogously, when all the elements in theeither . . . or construction are plural, the verb is plural too:
類似地，當所有either…or 結構中的成分都是複數的時候， 動詞也套用複數：
例句：
Either the Clarks or the Kays have been invited.
克拉克全家和凱全家都被 邀請了。

When the construction mixes singular and plural elements, however,there is some confusion as to which form the verb should take.It has sometimes been suggested that the verb should agree with whichever noun phrase is closest to it;thus one would writeEither Eve or the Kays have been invited, butEither the Kays or Eve has been invited. This pattern is accepted by 54 percent of the Usage Panel.Others have maintained that the construction is fundamentally inconsistent whichever number is assigned to the verband that such sentences should be rewritten accordingly.As Wilson Follett put it:
然而，當結構中既有單數又有複數成分的時候，動詞應採取什麼形式說法不定。人們有時建議動詞的人稱和數應與離得最近的名詞短語呼應；因此人們說Either Eve or the Kays have been invited ， 而不是Either the Kays or Eve has been invited 。 這種格式被用法使用小組54的成員所接受。也有人認為不管動詞用什麼樣的數， 這個結構本質上都是一致的，因此這樣的句子應重寫。象威爾遜·伏萊特所說的：
例句：
.This [construction] is defensible, but a workmanlike writer may put his pride in not writing sentences that need defending..See Usage Note at every ,neither ,or
.這個是站得住腳的，但是精心推敲的作者應以寫出不需為之辯護的句子而感到驕傲。.參見 every,neither,or