1、首先是詞性的區(qū)別：across為介詞,而cross為動(dòng)詞.
（動(dòng)詞為“穿過,橫穿”,名詞為“十字,十字路口”）
2、當(dāng)然across必須與through 區(qū)別開來.across為“橫穿”,與“道路”交叉形成“十字”.而through為在立體空間中的“穿過”.如：go through the forest“穿過森林”,go across the street “穿過大街”
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through表示“貫通、直穿、透過、穿過”的意思,即是從一頭（邊）貫穿到另一頭（邊）.
例The river runs through our city.這條河流經(jīng)我們市.
He passed through the hall.他穿過大廳
across表示“橫穿、橫過、橫渡、橫跨”
例：I swam across the Changjiang River 20 years ago.
20年前我橫渡了長(zhǎng)江.
Look left and right before you go across the street.
過馬路時(shí)要左右看.
through,across和over的區(qū)別
①、through：穿過
I threw it through the window.
Is it quicker to drive round the town,or straight though the centre?
②、across:from one side to the other
（在平面上）越過,在/到……對(duì)/面,橫過.
I can’t swim across the river.
我不能游到河對(duì)岸.
He went across the hall to the door.
他越過大廳到門口.
③、over:翻越過
across和over兩者都表示從一側(cè)向另一側(cè)的運(yùn)動(dòng)：
She drove over /across the bridge.
但如果越過的是一個(gè)高的物體,則用over:
He climbed over the wall.
如果越過的是一個(gè)平面,則宜用across：
He went across the hall to the door.
across和through都表示“穿過”,“通過”的意思,across表示從物體表面“穿過”、“通過”;而through則表示從內(nèi)部“穿過”、“通過”.