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介詞兼作其他詞性

一、介詞可兼用作副詞

英語中有一些介詞可以兼作副詞，這種介詞通常被稱作小品詞，比較常見的有：above, about, across, along, before, behind, below, besides, by, down, in, near, off, on, over, past, round, since, through, under, up等。這些詞有時也稱為副詞小品詞。請比較下面的例子：

Put your hat on. 把帽子戴上。(on為副詞)

Let’s sit on the grass. 咱們坐在草地上。(on為介詞)

Don’t knock the vase over. 別把花瓶碰倒了。(over為副詞)

Spread a cloth over the table. 在桌上鋪一塊桌布。(over為介詞)

He went up in the lift. 他乘電梯上去了(up為副詞)。

He ran up the stairs. 他跑上樓梯。(up為介詞)

I haven’t been away from home before. 我從前沒離開過家。(before為副詞)

Don’t talk like that before children. 在孩子面前不要這樣講話。(before為介詞)

二、介詞可兼用作連詞

英語中有少數介詞可以兼作連詞，比較常見的有after, before, since, till, until等。如：

After lunch it began to rain. 午飯后開始下雨。(after為介詞)

After you finish the letter show it to me．信寫完后給我看看。(after為連詞)

You must come home before dark. 你必須在天黑前回家。(before為介詞)

I always bathe before I go to bed. 我睡覺前總要洗個澡。(before為連詞)

I have been here since last week. 我從上周起一直在這里。(since為介詞)

She has had another baby since I saw her last. 從上次我見到她以來，她又生了一個孩子。(since為連詞)