It says "ik denk over haar na" is the correct answer. What is "na" there for? Why not just "ik denk over haar"?
It is not uncommon for Dutch prepositions to work in pairs, one before and one after the object of the sentence. I don't know if their is two much rhyme or reason to why.
So does noone really know why the word "na" is used?
The verb is nadenken, not denken.
Sorry to be difficult. But could you maybe use nadenken in a sentence so I can sorta understand it?. I'm that kind of learner.
Ik ben aan het nadenken. - I am thinking
Why not 'over'?
Prepositions are used differently in different languages, even very similar ones like English and Dutch. Also see my explanation about different types of denken here.
English is just as illogical. We can slow up or slow down. How can they possibly mean the same thing? But we only speed up never [speed down]. Where's the sense in that?
I have never heard anyone say "Slow up".
I think it's a very informal usage, that might be regional. I can hear a cowboy say: "Slow up there, pardner".
I answered "Ik denk aan haar" and it was accepted. Is it a valid sentence, does anyone know?
Yes, that is fine.
When to use over versus aan? My dutch husband just told me he would say ik denk over haar... and this is wrong... and he could not explain to me , as he would say it wrongly too
Can I use "vind" instead of "denk" in this sentence?
I thought "vind" is to find something, not to think of someone. I don't think it works in this example
oh ok! thanks!
Can you not write "ik denk van haar" i.e. i think of her ?
No, that sounds unnatural in Dutch. Can't tell you why - prepositions just often don't translate that straightforwardly between languages.
Why is d'r not accepted here, instead of haar ?
"D'r" is only used in speech and not in written form. :)
I think of her :'(