across 的用法
1. 無論用作介詞還是用作副詞，均可表示動(dòng)態(tài)意義或靜態(tài)意義：
(1) 表示動(dòng)態(tài)意義，意為“橫過”“到…的另一邊”。如：
Can you swim across? 你能游過去嗎? （副詞用法）
I cam swim across the river in 10 minutes. 我可以在10分鐘之內(nèi)游過河去。（介詞用法）
(2) 表示靜態(tài)意義，意為“在…的另一邊”。如：
My house is just across the street. 我家就在街道對(duì)面。（介詞用法）
We leave Dover at ten and we should be across in France by midnight. 我們10點(diǎn)鐘離開多佛，午夜時(shí)應(yīng)能抵達(dá)法國(guó)那邊。（副詞用法）
2. across from與from across都可以說，但含義稍有區(qū)別：
(1) across from 表靜態(tài)意義，意為“在對(duì)面”，與opposite同義，此時(shí)也可省略from只說across。如：
Just across from our house there's a school. 就在我們房子的對(duì)面有一所學(xué)校。
I'm staying at a little hotel just across from the Libyan Embassy. 我住在利比亞大使館正對(duì)面的一所小旅館里。
(2) from across 則表動(dòng)態(tài)意義，意為“從……的對(duì)面”。如：
He shouted to me from across the room. 他從房間的另一邊向我喊。
They waved at us from across the room. 他們從房間那一頭向我們招手。
3. 注意不要與動(dòng)詞cross弄混：
(1) 表示“穿過”時(shí)的用法比較：
It's dangerous for an old man to cross such a crowded street. 老人穿過這樣擁擠的街道很危險(xiǎn)。
It's dangerous for an old man to walk across such a crowded street. 老人穿過這樣擁擠的街道很危險(xiǎn)。
(2) 表示“交叉”時(shí)的用法比較：
The roads cross just outside the village. 那兩條路就在村外交叉。
He sat there with his arms across his chest. 他坐在那兒，兩臂交叉放在胸前。（介詞用法）
4. 用于習(xí)語come across，主要用法有：
(1) 偶然遇見，碰見（=run across）
Where did you come [run] across her? 你在那兒碰到她的?
I've just come across a beautiful poem in this book. 我在這本書里偶然發(fā)現(xiàn)一首優(yōu)美的詩。
(2) 被理解，被傳達(dá)（=come over）
He spoke for a long time but his meaning did not really come across. 他講了很長(zhǎng)時(shí)間，但他的意思沒有人真正理解。
(3) 使人產(chǎn)生某種印象（=come over）
Your speech came across very well. 你的演說相當(dāng)受歡迎。
He came across as sympathetic / a sympathetic person. 他給人以有同情心的印象。
注意以下用法，它不是習(xí)語，其中的across為副詞，表示“在另一邊”：
Come across to my office this afternoon. 你今天下午到我辦公室來一趟。