形容詞 both:

1. (used with count nouns) two considered together; the two

1. We can both run equally fast.
   我們兩個跑得一樣快。
2. She kissed him on both cheeks.
   她吻了他的雙頰。
3. He has known both grief and happiness.
   憂患和快樂他都經(jīng)歷過。
4. Proper diet and exercise are both important for health.
   適當(dāng)?shù)娘嬍澈瓦\(yùn)動對身體健康都很重要。
5. Good health may not only save your life, but it may save your love life as well. To bolster both, health experts advise following these6 steps.
   身體健康不僅可以挽救生命，還可以挽回你的愛情生活。要提高兩者的質(zhì)量，健康專家建議遵循以下6個步驟。
6. Both his eyes are hurt.
   他的兩眼都受傷了。
7. Both are good.
   兩者都好。
8. He is both a soldier and a poet.
   他既是個戰(zhàn)士，又是個詩人。

both

adj.（形容詞）
One and the other; relating to or being two in conjunction:
兩者的：一個和另一個；在連接詞中表示兩個或是兩個的：
例句：
Both guests have arrived. Both the books are torn. Both her fingers are broken.
兩個客人都已到了。兩本書都撕爛了。她的兩個手指都斷了

pron.（代詞）
The one and the other:
一個和另一個：
例句：
Both were candidates. We are both candidates. Both of us are candidates.
兩個都是候選人。我們都是候選人。我們兩個都是候選人

conj.（連接詞）
Used withand to indicate that each of two things in a coordinated phrase or clause is included:
與and連用：與and 連用以表明并列短語或從句中的兩個事物之一均包含在內(nèi)：
例句：
both men and women; an attorney well regarded for both intelligence and honesty.
男人和女人；才智和聰明均受好評的律師

來源：
Middle English bothe
中古英語 bothe
from Old English b3 th3 [both those]
源自 古英語 b3 th3 [那兩個]
b3 [neuter of] bôgen [both]
b3 [] bôgen的中性 [兩個]
th3 [plural of] thôt [that] * see that
th3 [] thôt的復(fù)數(shù) [那] *參見 that

Both is used to indicate that the action or state denoted by the verb applies individually to each of two entities. Both books weigh more than five pounds, for example, means that each book weighs more than five pounds by itself,not that the two books weighed together come to more than five pounds.Both is inappropriate where the verb does not apply to each of the entities by itself. · In possessive constructionsof both is usually preferred: the mothers of both (rather than both their mothers ); the fault of both (rather than both their fault or both`s fault ). · Whenboth is used with and to link parallel elements in a sentence, the words or phrases that follow them should correspond grammatically:in both India and China or both in India and in China (not both in India and China ). See Usage Note at and
Both 用于表明動詞意指的行為或狀態(tài)，可單獨(dú)用于兩個實(shí)體中的任一個。 例如兩本書均重于五磅， 意指每一本書自身即重過五磅，而不是兩本書合起來才重過五磅。當(dāng)動詞不能單獨(dú)用于實(shí)體中的任一個時，用both 是不恰當(dāng)?shù)摹?在所有格結(jié)構(gòu)中，of both 通常是更確切的： the monthers of both（他們的母親） （而不是 both their monthers ）； the fault of both（他們的過錯） （而不是 both their fault 或 both`s fault ）。 當(dāng)both 與 and 在句子中用于連接平行成份時， 連接的詞或短語應(yīng)在語法上保持一致：in both India and China （在印度和中國）或 both in India and in China （而不是 both in India and China ） 參見 and