Which one is correct?

[www_dba]

As I cannot login and reply, I have to post it again. Sorry.

Dear teachers,
Which one is correct?
My English has been improved.
My English has improved.

I was told that
The active voice one is natural. The passive sentence simply does not exist in real English.
Is it correct?

Another question
Should I say 'I come from China' or 'I came from China'?
Which one sounds more natural?

TIA

[blacknomi]

My English has improved or my English is improving.


Where are you from? Where do you come from?
I'm from China. I come from China. ( It may imply that he is a Chinese.)


Where did you come from?
I came from China. ( Maybe this person is travelling around the world. He is now in Australia and his last stop was Beijin.)