1. 表示“反對(duì)”，其反義詞為 for。若表示“強(qiáng)烈反對(duì)”，一般用副詞 strongly：
    Are you for or against the plan? 你對(duì)這個(gè)計(jì)劃是贊成還是反對(duì)呢?
    Public opinion is strongly against hisvisit to the country. 輿論強(qiáng)烈反對(duì)他訪問這個(gè)國家。
    表示“反對(duì)”，經(jīng)常同那些與之含義相關(guān)的動(dòng)詞連用 (如：fight, struggle, protest, argue, guard等)：
    The soldiers fought againstthe enemy bravely. 士兵們勇敢地打敵人。
    He struggled againstthose who opposed his plan. 他同那些反對(duì)他的計(jì)劃的人作斗爭(zhēng)。
    2. 表示位置，意為“靠著”、“頂著”、“迎著”、“襯著”等：
    The teacher’s desk is against the wall. 老師的辦公桌靠墻放著。
    He stood leaning against the tree. 他站著斜靠在墻上。
    Thered flag looks very bright against the blue sky. 紅旗在藍(lán)天的襯托下顯得十分鮮艷。
    3. 注意 against 是介詞，不是動(dòng)詞，將其用作動(dòng)詞是錯(cuò)誤的：
    正：I leaned against the wall. 我斜靠在墻上。
    正：I’m against his idea. 我反對(duì)他的意見。
    誤：I againt the wall. / I against his idea.