I need help with the subordinate clause, and op/aan, and more...
I am confused with how the word order changes when there is a subordinate clause. I've been to dutchgrammar.com but it doesn't help much (at least for me).All I understand is that any word that divides the sentence into two "mini" sentences you move the verb of the second "mini" sentence to the end of the whole sentence; but on the dutchgrammar.com website it got more complicated. Besides this I think I understand word order pretty well
Also this is kinda unrelated to the original question but why do some prepositions (op, aan, bij) change their definition sometimes? I'm getting used to seeing aan as 'to' but I don't understand when to use op or aan to mean 'on' and bij means 'at' or 'by' most of the time but then there's op, first it means 'on', and now 'to' and then it's randomly in a sentence. Can someone explain this to me
How do you pronounce een? With the new male voice it sounds like uh(n) but the old voice was more ayn.
Could you give a more specific example concerning the subordinate clause?
Then about 'aan' and 'op'. Op is usually used to say something like: het brood op tafel (the bread on the table). It will also be used to refer to a moment, day, or event: op zaterdag, op dat moment, op Kerstavond, op Pukkelpop (a Belgian music festival). 'Aan' will not be used in such a way. It can translate to 'on' as opposed to 'off'. So: ik zet de televisie aan, I turn on the television. Furthermore, 'aan' could mean on as in 'attached to something': het schilderij aan de muur (the painting on the wall). The difference between the two is important indeed: if I say "ik zit aan tafel", I am sitting at the table, I really say something different than "ik zit op de tafel", I am sitting on the table.
So: if you want to say on a certain surface, you will want to use 'op'. It becomes more difficult with 'on the wall' I guess. I think you should keep the 'attached to' thing in mind. I would interpret een schilderij 'op' de muur as a painting actually painted on the wall itself, instead of on canvas. That canvas would be 'aan de muur'. Additionaly, 'aan' could mean 'to'. So: ik stuur een brief aan jou, ik geef een cadeau aan jou. Aan can, like you said, also mean 'by', as in 'aan het water', by the water.
Remember that both 'aan' and 'op' can be part of a verb. Such verbs will split in many sentences, like 'ik draag iets aan' (I suggest something). In these cases you will just have to learn the verbs like in other languages.
I hope I've helped you a bit. If not, please let me know, I'll try to explain things in a different way.
Good luck learning Dutch!
For the subordinate clause, I don't understand where you move the verb and how sometimes the subject moves as well. For op I saw it in a sentence as opgegeten which I guess opeten is a variation of eten. And I didn't know aan could mean by. I guess I'll have to remember many phrases with prepositions like houden van. Also where do you put er in a sentence? I did go to dutchgrammar.com but I don't understand where you move it in a basic sentence (today I went to buy things there). I don't remember the sentence but op did mean 'to'; maybe it was part of a prepositional verb and I just didn't notice that
The subordinate clause (bijzin) in Dutch has a subject–object–verb (SOV) order (https://en.wikipedia.org/wiki/Subject%E2%80%93object%E2%80%93verb#Dutch). So it differs from English, that uses the SVO order. The SOV order will usually be the right order to use. In the so-called 'beknopte bijzin' (non-finite clause) the subject is omitted, and so the SOV order does not work. In general, though, the SOV order should work.
In the case of 'opeten' 'op' gets its meaning from an adjective. As an adjective 'op' has the meaning of 'no more', like 'het eten is op'. So the sentence "Ik ben een broodje aan het opeten" would not just mean "I am eating a sandwich". By adding 'op' it is made clear that I am not leaving half of the sandwich, I am eating it until there's nothing left.
'Er' can mean several things. It can be used in five different ways (It is not the easiest word in Dutch). This means that 'er' does not always take the same place.
Firstly it can refer to a place. So: Ik woon al een tijd in Leuven (I have been living in Leuven for a while already), will become "Ik woon er al een tijd". Er refers to the city of Leuven that I am omitting in the 'er' sentence. It does not take the accept same place in the sentence, as you see, the word 'al' (already) is after er, instead of in front 'in Leuven'. Or 'Hij is nog niet thuis' becomes 'Hij is er nog niet'.
Secondly it can be combined with a preposition. "Ligt het brood op tafel? Ja, het ligt erop." Notice that er in "erop" refers to tafel.
Thirdly, it can have the meaning 'of it'. It will come with a number. In this meaning, the word is often not necessary in English. "Heb jij veel chocoladerepen? Ik heb er vier", meaning: Do you have many chocolate bars? I have got four (of them)". The 'of them' could be omitted, but in Dutch you will have to add 'er'. 'Er' will come in front of the number.
'Er' can also be used in passive sentences. 'Er is gevoetbald' (Football was played). Er will be used if the passive sentence does not have a subject. 'Er' will come first in the sentence.
Finally, 'er' can also be used to refer to the subject later on in the sentence. This subject must have an indefinite article in front of it, though, so no 'de' or 'het', but always 'een'. "Er loopt een man in het bos". Er refers to 'een man'. The sentence would mean the same if you would say "een man loopt in het bos". It sounds less natural, though. 'Er' will come first in the sentence.
This is my source: http://educatie-en-school.infonu.nl/taal/27737-het-gebruik-van-het-woord-er-in-het-nederlands.html. It is all in Dutch, however, so I translated it for you in this post. But if you want you can find more sentences with 'er' on this site.