帮我检查一下英语作文有什么语法错误的地方.This afternoon,I went shopping with my mom.While we walking around in the shop.I saw a foreigner in men's department.He wanted to buy a pair of shoes,but he couldn't talk to the salesgirl,because he couldn't speak Chinese,the salesgirl could't hear English at all.I knew it's very difficult for the foreigner to buy his shoes like that.So I translated for them .At last the foreigner bought his shoes and said thanks to me ,my mother

This affternoon, I went shopping with my mum. While walking around in the shop, I saw a foreigner in Men's Department. He was trying to buy a pair of shoes. It looked there was a commucation problem because he could not speak Chinese, and the sales girl could not understand English at all. I knew it's very difficult for the foreigner and the sales girl. So I interpreted for them. In the end, the foreigner bought his shoes and thanked me for helping him. My mum also praided me for helping the foreigner. So I felt very happy indeed.
Your writing is very good in general. I've changed a few bits to make it sound more natural for the English readers. Good try and good luck with everything!

This afternoon， I went shopping with my mom.While we were walking around in the shop, I saw a foreigner in men's department. He wanted to buy a pair of shoes, but he couldn't talk to the salesgirl, because he couldn't speak Chinese, the salesgirl could't understand English at all. I knew it was very difficult for the foreigner to buy himself shoes like that, so I translated for them .At last, the foreigner bought himself shoes and said thanks to me , my mother also praised me that I had given a hand to the foreigner. So I felt very happy.
还行，继续努力

While we walking around in the shop这个应该改为When we were walking aroud the shop.
the salesgirl could't hear English at all.前面加个and the salesgirl couldn't understand English at all
I knew it's 改成I knew it was
,my mother also praised me that I gave a hand to the foreigner.这句重起一句,My mothe also praised me fot giving a hand to the foreigner