Translation of "分からないな" in English

I don't know Russian.

I don't know if I still have it.

I'm not familiar with French poets.

I don't get what you mean.

- I'm unsure about who I should vote for.
- I'm not sure who to vote for.
- I’m on the fence on who I should vote for.

Now, I'm not sure how easy it would be to climb back out.

I don't know if he knows it.

I'm not sure when Tom will get back.

- I'm not sure Tom can do that again.
- I'm not sure that Tom can do that again.

I don't get what you mean.

I'm not familiar with French poets.

- I don't get what you mean.
- I don't understand what you mean.

I don't know what you mean.

I don't know if he knows it.

I don't know exactly where Tom is.

- I don't know at all why he quit his job suddenly.
- I have no idea why he quit his job suddenly.

- I'm at a loss for words.
- I don't know what to say.