against是什麼意思？

例句：

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

會議上普遍的意見是反對這個決定。

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

新的資料和電腦中已有的`數據作了比較。

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

我不想違背您的意願。

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

老師們最近面臨着一些重大問題。