as的用法：
1、as做介詞，意思是“作為”
例句：
French is known as the most beautiful language in the world.
法語(yǔ)以世界上最美麗的語(yǔ)言著稱(chēng)。
2、as做連詞，引導(dǎo)時(shí)間狀語(yǔ)從句，意思是“當(dāng)……的時(shí)候”
例句：
My mother was cooking fish as I arrived home.
當(dāng)我到家的時(shí)候，我媽媽正在做魚(yú)。
3、as做連詞，引導(dǎo)原因狀語(yǔ)從句，意思是“因?yàn)椤?/p>
例句：
As rain has fallen, the air is cooler.
因?yàn)橄逻^(guò)雨，所以空氣比較涼爽。
4、as做連詞，引導(dǎo)讓步狀語(yǔ)從句，意思是“雖然”
例句：
Young as he is, he has been one of the most famous painters in our country.
雖然他還很年輕，但已經(jīng)成為我們國(guó)家最有名的畫(huà)家之一。
5、as做連詞，引導(dǎo)方式狀語(yǔ)從句，意思是“以……方式”
例句：
Do as the Romans do when in Rome.
入鄉(xiāng)隨俗
6、as做關(guān)系代詞，引導(dǎo)定語(yǔ)從句：
例句：
This is the same game as I played yesterday.
這和我昨天玩的游戲一樣。