against
preposition /əˈɡenst/,  /əˈɡeɪnst/
  /əˈɡenst/,  /əˈɡeɪnst/
For the special uses of against in phrasal verbs, look at the entries for the verbs. For example count against somebody is in the phrasal verb section at count.Idioms - opposing or disagreeing with somebody/something
反对;与…相反;逆;违反 - the fight against terrorism
反对恐怖主义的斗争  - We're playing against the league champions next week.
下周我们要和联赛冠军队比赛。  - We were rowing against the current.
我们划船逆流而上。  - That's against the law.
那是违法的。  - She was forced to marry against her will.
她被迫违背自己的心愿嫁了人。  - Are you for or against the death penalty?
你赞成还是反对死刑?  - She is against seeing (= does not want to see) him.
她不想见他。  - I'd advise you against doing that.
我劝你别做那事。  
 - the fight against terrorism
 - not to the advantage or favour of somebody/something
对…不利 - The evidence is against him.
证据对他不利。  - Her age is against her.
她的年龄对她不利。  
 - The evidence is against him.
 - close to, touching or hitting somebody/something
紧靠;倚;碰;撞 - Put the piano there, against the wall.
把钢琴放在那儿,紧靠着墙。  - The rain beat against the windows.
雨点击打着窗户。  
 - Put the piano there, against the wall.
 - in order to prevent something from happening or to reduce the damage caused by something
以防 - an injection against rabies
狂犬病预防注射  - They took precautions against fire.
他们采取了防火措施。  - Are we insured against theft?
我们保了盗窃险没有?  - He gritted his teeth against the pain.
他咬紧了牙忍着疼  
 - an injection against rabies
 - with something in the background, as a contrast
以…为背景;衬托 - His red clothes stood out clearly against the snow.
他的红衣服在白雪中格外显眼。  -  (figurative) The love story unfolds against a background of civil war.
这爱情故事以内战为背景展开。  
 - His red clothes stood out clearly against the snow.
 - used when you are comparing two things
和…相比 - You must weigh the benefits against the cost.
你一定要权衡利益与成本二者的得失。  - Check your receipts against the statement.
核对你的收据与结算单是否相符。  - What's the rate of exchange against the dollar?
与美元的兑换率是多少?  
 - You must weigh the benefits against the cost.
 
词源Middle English: from again + -s (adverbial genitive) + -t probably by association with superlatives (as in amongst).
Idioms 
as against something 
- in contrast with something
与…相对照;和…相比较 - They got 27 per cent of the vote as against 32 per cent at the last election.
他们获得了27%的选票,而上次选举时为32%。  
 - They got 27 per cent of the vote as against 32 per cent at the last election.
 
the cards/odds are stacked against you 
- you are unlikely to succeed because the conditions are not good for you
 Topics Difficulty and failurec2形势对你不利