1. 永远;永恒;永久
    If you say that something will happen or continue forever, you mean that it will always happen or continue.

    e.g. I think that we will live together forever...
           我想我们会永远生活在一起。
    e.g. It was great fun but we knew it wouldn't go on for ever...
           这很开心，但是我们知道不会永远这样。

2. 完全地;永恒地
    If something has gone or changed forever, it has gone or changed completely and permanently.

    e.g. The old social order was gone forever...
           旧的社会秩序一去不复返了。
    e.g. Their lives changed forever.
           他们的生活完全改变了。

3. 长久地;无尽头地
    If you say that something takes forever or lasts forever, you are emphasizing that it takes or lasts a very long time, or that it seems to.

    e.g. The drive seemed to take forever...
           车似乎永远也开不到头。
    e.g. They didn't cost anything and they lasted forever.
           它们花不了多少钱，却非常耐用。

4. 老是;没完没了地
    If you say that someone is forever doing a particular thing, especially something which annoys or amuses you, you are emphasizing that they do it very often.

forever

    e.g. He was forever attempting to arrange deals...
           他老是想撮合交易。
    e.g. I was forever dragging him away from the fireplace.
           我老是要把他从壁炉边拉开。

5. 总是;始终
    You use forever to emphasize that someone always has or shows the quality mentioned.

    e.g. Katherine was forever secretive...
           凯瑟琳总是神神秘秘的。
    e.g. To this end the young child is forever watchful.
           这个年纪不大的孩子为此始终保持警惕。