英文语法.帮我改一下tenses

英文语法.帮我改一下tenses
I visited my old school and all the memories felt so fresh and new as if it had all happened yesterday.Everything is still there,the same old playground and the same scar on my left knee.
Now,the skinny tall girl stood still on the playground except this time,there was no oak tree for me to lean on.All was there except for my old wise oak tree.
The old gardener told me that the oak tree passed away 3 years ago.It might be no longer there but it is still deeply rooted in my memories.The leaves might have crumbled and disappeared but I still have the little tree branch.
The tree probably has helped more children like me during the past 15 years.I’m sure about that.