名詞 half:

1. one of two equal parts of a divisible whole
   同義詞：one-half
2. in various games or performances: either of two periods of play separated by an interval

形容詞 half:

1. consisting of one of two equivalent parts in value or quantity
2. partial
3. (of siblings) related through one parent only

副詞 half:

1. partially or to the extent of a half

1. The food's not half bad.
   這食物挺不錯。
2. Half of them are here.
   半數(shù)人來了。
3. The girl left her homework half done.
   這女孩只做完了一半作業(yè)。
4. Half the car was damaged.
   車子毀了一半。

half

n.（名詞）
【復(fù)數(shù)】 halves[h2vz, hôvz]
Abbr. hf.
縮寫 hf.
One of two equal parts that together constitute a whole.
一半：一起組成一個整體的相等的兩部分中的一個
One part approximately equal to the remaining part.
半部分：與余下的部分大致相當(dāng)?shù)牟糠?/br>Informal A 50-cent piece.
【非正式用語】 一個50美分的硬幣
Sports
【體育運(yùn)動】
One of the two playing periods into which certain games are divided.
半場：某些體育比賽被劃分成兩個階段，其中之一被稱為半場
A halfback.
中衛(wèi)
Chiefly British A school term; a semester.
【多用于英國】 半學(xué)年：學(xué)校術(shù)語；一學(xué)期
Half an hour:
半小時：
例句：
a half past one.
點(diǎn)半

adj.（形容詞）
Abbr. hf.
縮寫 hf.
Being one of two equal parts.
一半的：兩個相等物之一的
Being approximately a half.
大約一半的
Partial or incomplete:
部分的，不完全的：
例句：
gave me a half smile.
對我似笑非笑

adv.（副詞）
To the extent of exactly or nearly 50 percent:
大約一半地：正好或差不多達(dá)到百分之五十的程度：
例句：
The tank is half empty.
油箱是半空的

Not completely or sufficiently; partly:
不徹底地或不充分地；部分地：
例句：
only half right.
不完全正確

<習(xí)慣用語>by half
By a considerable extent.
以可觀程度地
By an excessive amount:
過度地：
例句：
too clever by half.
過于聰明

by halves
In a reluctant manner; unenthusiastically.
不熱情地：采取一種勉強(qiáng)的態(tài)度；不熱情地
in half
Into halves.
成為相等的兩半
not half
Not at all:
一點(diǎn)兒也不：
例句：
.Fancy housingô Not half likely, ma`am.(Russell Baker)
.上妓院ô根本不可能，女士.(拉塞爾·巴克)

not the half of
Only a fraction or a small part of.
只有一個片斷或一小部分
來源：
Middle English
中古英語
from Old English healf * see skel-
源自 古英語 healf *參見 skel-

The phrasesa half, half of, and half a or half an are all correct, though they may differ slightly in meaning.For example,a half day is used when day has the special sense .a working day,. and the phrase then means .4 hours.. Half of a day and half a day are not restricted in this way and can mean either 4 or 2 hours.
短語a half，half of 和 half a 或者 half an 都是正確的， 盡管它們可能在意義上稍有不同。例如當(dāng)day 當(dāng)工作日來講時， a half day 這個短語的意思是.四個小時.。 Half of a day 和 half a day 的意思不限于此， 它們可以表示四小時或者十二小時