against是什么意思？

例句：

1、The general feeling of the meeting was against the decision.

会议上普遍的意见是反对这个决定。

2、New information is matched against existing data in the computer.

新的资料和电脑中已有的`数据作了比较。

3、I don't want to go against your will.

我不想违背您的意愿。

4、Teachers are up against some major problems these days.

老师们最近面临着一些重大问题。