1. 用作介詞,，主要表示“作為”“當(dāng)作”“充當(dāng)”“如同”等。如：

He treats me as a child. 他把我當(dāng)小孩看待,。

As your doctor, I advise you to eat less. 作為你的醫(yī)生,，我建議你少吃點(diǎn)。

另外,，它還可表示“當(dāng)……時(shí)候”“例如”,。如：

As a child he was sent to six different schools. 他兒時(shí)前后上過(guò)6所學(xué)校。

I was wearing clothes for dirty work, as when gardening. 我穿著做粗活的衣服,，例如栽花種草時(shí)所穿的衣服,。

2. 用作連詞,，注意以下用法：

(1) 表示“隨著”，后接句子,。如：

As time passed, things seemed to get worse. 隨著時(shí)間的推移,，情況似乎變得更糟了。

若其后不接從句,，而接名詞,，則用介詞 with 表示“隨著”。如：

With the development of modern agriculture and industry, more and more waste is produced. 隨著現(xiàn)代工農(nóng)業(yè)的發(fā)展,，污染越來(lái)越嚴(yán)重了,。

(2) 表示讓步，意為“雖然”“盡管”,，要用于倒裝句（相當(dāng)于 though,，但語(yǔ)氣稍弱）。如：

Boy as he was, he behaved like a girl. 他雖然是個(gè)男孩,，但舉止卻像個(gè)女孩,。

Much as I like you, I couldn’t live with you. 我盡管很喜歡你，卻不能和你一起生活,。

Try as he would [might],，he couldn’t open the door. 他試過(guò)多次了，卻仍打不開(kāi)門(mén),。

該用法請(qǐng)參見(jiàn)although詞條,。

(3) 表示時(shí)間，意為“當(dāng)……時(shí)候”,。如：

He dropped the glass as he stood up. 他站起來(lái)時(shí),，把杯子摔了。

As I was coming here, I met your brother. 我來(lái)這里時(shí)碰到了你的弟弟,。

注意,，as引導(dǎo)時(shí)態(tài)狀語(yǔ)從句時(shí)，其謂語(yǔ)動(dòng)詞通常只能是動(dòng)作動(dòng)詞,，而不能是靜態(tài)或狀態(tài)動(dòng)詞,。如：

她出生后不久父母雙亡，是由姑母撫養(yǎng)大的,。

誤：Her parents died as she was a baby and she was brought up by her aunt.

正：Her parents died when she was a baby and she was brought up by her aunt.

但是,，當(dāng)as用于引導(dǎo)原因狀語(yǔ)從句時(shí)，從句謂語(yǔ)可以是靜態(tài)動(dòng)詞或狀態(tài)動(dòng)詞,。如：

As you weren’t there I left a message. 因?yàn)槟悴辉谀抢?/FONT>, 我留了個(gè)信兒,。