它的形成、发展、壮大和弱变，虽然有偶然的因素，但更多的是复杂的社会历史背景。

Its formation, development, growth and weak, although there are occasional factors, but is more complex social and historical background.

youdao

在最初的几个月里，这种免疫反应最强，但是在随后的几年里则会越变越弱。

The response is strongest within the first several months, and then diminishes over the following years.

youdao

随着我们年龄的变老，我们的皮肤在转换阳光到维他命d的能力也越来越弱。

As we age, our skin becomes less effective at converting sunlight to vitamin D.

youdao

And I forget where Napoleon actually dies, but he's got memories of getting sick and ill and the light begins to fade and he goes unconscious.

我不记得拿破仑在哪里去世了，但他有生病的记忆,生命之光慢慢变弱，然后失去了意识。

耶鲁公开课 - 死亡课程节选

improve your range of motion and strengthen those muscles, they get weaker during that process

改善你的运动范围并加强这些肌肉，它们就会在运动过程中变弱，

健康生活 - SpeakingMax英语口语达人