prep.  反对

prep. 〔行为〕违背，与…相悖

prep.  〔法律或法规〕禁止

prep.  对…造成伤害[威胁，不利]

prep.  倚着，靠着

prep.  逆

prep.  防，抗

• be/come up against sb/sth 

  必须面对某人/某事

• have sth against sb/sth 

  不喜欢[不赞成]某人/某事

• The arguments against physical education have included concerns that gym time may be taking away from study time.

  反对…的争论

• The biggest concern with robots going against human values is that human beings fail to do sufficient testing and they've produced a system that will break some kind of taboo (禁忌). 违背

• It launched a fierce attack against Islamic State. 针对…的袭击

• At the end of the day, these kinds of systems are primarily designed to protect against the sort of opportunistic smash-and-grab attack that makes up the majority of burglaries. 以防

• Its effects on the global economy go against existing economic laws. 违背法律

• When you think you're lost, sit down on a log or rock, or lean against a tree, and recite something you have memorized to bring your mind to a point where it is under control. 靠着一棵树

• And the best defense against memory loss is to try to prevent it by building up your brain's cognitive (认知的) reserve, Daffner says. 对抗失忆

• They could fly against a strong wind. 

  逆风飞行

• You see, this is what we’re up against – the suppliers just aren’t reliable. 你瞧，这就是我们必须面对的难题，供应商就是靠不住。

BrE /əˈɡenst/

NAmE /əˈɡenst/