Once an earthquake was happened in a small town.Everyone in

Once an earthquake(将was去掉) happened in a small town.Everyone in the town believed （that引导宾语从句）there would soon have another earthquake.As many of their friends ,Mr and Mrs.Smith place（piaced本文用的是过去时态）."I will send John to my brother Perter,whose（改为who,因为whose是所有格,不能单独用作主语） lives a long way away," Mr.Smith said.He telephoned Peter and asked him that（whether） he will（改为could） let John live with him.Mr Smith promised," John won't give you any troubles" John finally went to live with his uncle.Several days later ,Mr.Smith accepted a phone call from peter ,who said ,"I'm returning John.Sending（Send祈使句用动词原形开头） me an earthquake instead of him.""

将was happened改为happened,因为在这里需要的是过去式，而不是过去式的被动语态，而且happen没有被动语态。
place改为placed.斯密斯夫妇和他们的朋友们安顿下来了。我不知道这里用‘place’对不对，但得用过去式。
好像a long way away错了吧。它是‘离开很远’的意思，who lives far from here. whose也错了。

was happened不对，发生没有被动的
believe 后加that
有事要下，自己再看看啊