I live in a small town where life is quiet and relaxing. Last week, I decided to go on a trip to a big city. I had heard many good thing about it, so I was really excited. As soon as I arrived, I was surprised to see how different the city was. The skyscrapers were so tall and the streets were so crowd. I walked around the city for hours, looking at the shops and restaurants. But the most amazing thing I saw was a performance by street artist. They were painting beautiful pictures with chalks on the ground. I was so impress that I bought one of their paintings. It was a real pleasure to see such talent in the street.

解析：

1.错误：thing
改正：things
解析：名词“thing”应该使用复数形式“things”，因为前面有“many”修饰，表示多个事物。

2.错误：crowd
改正：crowded
解析：这里需要用形容词“crowded”来修饰“streets”，表示街道很拥挤。原词“crowd”是名词，不符合句意。

3.错误：street artist
改正：street artists
解析：由于前面提到的是“the most amazing thing I saw was a performance”，说明表演是由多个街头艺术家完成的，所以“artist”应该使用复数形式“artists”。

4.错误：chalks
改正：chalk
解析：“chalk”作为绘画材料时是不可数名词，因此不需要加“s”变为复数形式。

5.错误：impress
改正：impressed
解析：这里需要使用形容词“impressed”来表达“我被他们的画作所打动”，而不是动词“impress”。