"She said something which I don't understand".

[MeyaN]

"She said something which I don't understand". Listener can easily understand this as using "I don't" makes it obvious that the speaker didn't know it before too.
But here tenses don't agree as "said" and "don't" are different tenses.

"She said something which I didn't understand. I still don't". Here adding "I still don't" gives unnecessary importance to that fact and makes it verbose.

So, how do I structure the sentence without slipping on grammar and also mentioning that I still don't understand ?

Thank you.

 

[MeyaN]

But, that's not acceptable in writing. Right?

 

[MeyaN]

So, how do I do it in written communication? Also please suggest me alternatives.

 

[Rover_KE]

But[no comma here] that's not acceptable in writing. Right?

Who told you that?

 

[bigC]

Is it correct to use "I didn't"?

If it is correct, then is there any difference between using "I don't" and "I didn't"?

 

[MeyaN]

Comma is optional, right? I used it to give a pause. Is it wrong?

Please tell me why do you consider it incorrect.

 

[Tarheel]

Say:

But that's not acceptable in writing. Right?

It's common to use a comma before "but"; it's not at all common to use a comma after "but".

 

[bigC]

Yes. If you say didn't, you are restricting the time period of your reaction to the past time of her saying something; it allows the possibility that you now understand it. That possibility is excluded if you use don't.

Your answer seems conflict with post #2

 

[ChinaDan]

Your answer seems conflict with post #2

Here is a past tense story.

Last weekend, I went for a walk, and took pictures of boats that sailed on the Chang Jiang; a river that runs through the heart of Wuhan.

Notice all the blue (past tense) verbs. And one red (present tense) verb. Even though I'm telling you of an event that occurred in the past, I use the present tense for the river because it is a permanent feature. It was running before, it runs now, and will probably keep running in the future.

What Piscean was pointing out is that, in the original OP sentence, the use of the present tense don't while telling a past tense story invokes this "permanency". It signals to the reader that this state was true at the time of the story, and is still true now. Changing to didn't leaves the possibility open that the speaker does in fact understand now.

Personally, I'd take it a step further and, assuming the speaker was a native English speaker, I would infer that choosing to say didn't means you do understand now.

Note I said infer. Grammatically, Piscean is spot on. However, in human interaction, we fill in a lot of stuff that is not explicitly stated or follows a rule. My experience tells me that if a native speaker still didn't understand, they would not chose didn't in this sentence because they understand that saying don't is more accurate.

It's like those pesky multiple choice exams with more than one correct answer, but you are expected to chose the "more" correct answer.:-?