帮忙看下有无语法错误~

一If we stumbled, we had to learn to climb up. 这句话应该是现在时态吧
二Don’t be staggered，try to solve it in your own ways.这句话应该是Don't be staggered and try to solve it in your own ways.

三 If someone run downstairs quickly，
and doesn't pay attention to steps
or fight with someone else on the
steps, maybe he will...这里的动词run应该为单数形式，runs
四He stumbled at a step, and his leg was injured.为什么这突然变成一般过去式了呢？如果你后面是过去的事的话，那run就不改，把doesn't改为didn't
五 stagger时态有误，然后应该是stagger on going to... ...

注意人称的一致,时态的一致.还有一些小地方如单复数.冠词.

个人意见:如果是小作文.建议重写.写得正式些.如果是演讲稿..就无所谓了.

错误倒没有，只是用了两个if引导的状语从句，何必重复呢？
If we stumbled, we had to learn to climb up.可以用分词短语作状语。
If we stumbled，改成stumbled，直接省略if we.这样更好。

The sign tell us:
be careful or you will be stumbled.
改成宾语从句：The sign suggest that we be carful or be stumbied.更好，用了冰语从句中虚拟语气的用法。

应该可以了。希望能帮到你。