both、all有何區別
all全、都（三者以上），既可修飾可數名詞也可修飾不可數名詞。
All the books are useful to us.
All knowledge comes from practice.
all與否定詞not連用為“部分否定”，表示“不是所有的……都……”
I don't know all of them. 他們當中我並不都認識。
All don't agree with you.=Not all agree with you. 並非所有人都同意你。
both兩者都
You can take both of them.兩個你都可以拿去。
與否定詞連用表示“部分否定”。
I don't know both of them.他倆我並非都認識。
both...and...雙方都……
He can both sing and dance.他能歌善舞。
both和all詞義辨析
1、both 只能與複數的可數名詞連用，與可數名詞的`複數形式連用時,both則指兩個。
You were both a prey to compulsions.你倆都太沖動了。
2、all可與可數名詞的單、複數或不可數名詞連用，與可數名詞的複數形式連用時, all指三個或三個以上。如：
All children deserve encouragement.所有的孩子都應得到鼓勵。