1.against作“反对”解时反义词是for。
2.against用在fight,strive,struggle等词后面,同with意思相同,不过against更强调一种困难中的反抗。
We fight for the weak against the strong.
3.作为介词,against后接的宾语有时可省略。
We have saved some money against our old age.
我们存了一些钱,以备老年之用。
Our defences must be reinforced against attack.
我们必须加强防御设施以抵御进攻。
His eloquence did not avail against the facts.
他的雄辩在事实面前不起什么作用。