They forgot that one has to be for something and not just against everything.

参考译文：他们忘记了，一个人必须是为了某件事，而不仅仅是反对一切。

解答如下：forget为静态动词，静态动词用用去时态表示过去的状态，宾语从句谓语动词be for为静态动词，静态动词是一个从过去到现在到将来长期存在，或者不会结束或者结束不可以预料。因此用一般现在时态。

A desire to sell gold appeared to have been worsened by thinking that concerns about the Greek economy have somewhat eased.

参考译文：考虑到对希腊经济的担忧有所缓解，抛售黄金的欲望似乎已经恶化。

(1)appeared用一般过去时态表示动作发生在过去。

(2)to have been worsened不定式完成体表动作发生在appeared之前。