What's wrong with this sentense ?

[Kumiko1225]

Hello !

I need to know which part of this sentense is wrong.

I have been to China several times while I was a student.

Should it be "when I was a stundent " or "while I was at school "?

Also, is there any big difference in meaning of the following sentenses ?

1. She can't be so far.
2. She cannot have gone so far.
3. She couldn't have gone so far.

Thanks in advance !

[Beeesneees]

The tense is wrong. This is correct:
I went to China several times while/when I was a student.
I went to China several times while/when I was at school.

Compare with:
I have been to China several times in the past three years.
I have been to China several times in my life.
I have been to China several times.

'so far' is incorrect.
She can't be too far.
She cannot have gone too far.
She couldn't have gone too far.
She can't be too far away.
She cannot have gone too far away.
She couldn't have gone too far away.
_________________
Cheers m' dears!

[Bwriter]

[Beeesneees]

I don't feel that 'I have been to...' works with your first sentence.
'I had been to..' would be acceptable, if using it as a reference point for a visit on another occasion in the past or to give an explanation. For example:
I had been to China several times while I was a student, so I knew what to expect when I visited again last year.
I had many photographs of China because I had been there several times while I was a student.

The subjunctive is correct.
_________________
Cheers m' dears!

[Kumiko1225]

Dear Beesnees, Bwriter

Thanks for your replies !

I think I understood about the first question.

As for the second question, can I say "so far yet" instead of "so far" ?
like
She cannot be so far yet.

Thanks !

[Beeesneees]

Usually the term is 'too far'.
_________________
Cheers m' dears!

[Bwriter]

Oh thanks! I wrote about Past Perfect and built a sentence with Present Perfect. I didn't even see this until you answered :) And thanks for examples - they helped a lot!