Thank you. It was very underatandable and helpful what you have written. :)

Your last sentence is one of this kind as well. "Ik had een afspraak met meneer Janssen staan om 10 uur, maar mijn auto ging ineens kapot. Ik baalde, want dan zouden we de afspraak moeten verzetten. Gelukkig gaf mijn vriend me een lift, zodat ik toch nog op tijd kwam." Lastly, 'zouden' is used like 'should' in English: "Should he call Mr. Janssen?" - "Zou hij meneer Janssen moeten bellen?" "You should call Mr. Janssen." - "Je zou meneer Janssen moeten bellen." That's pretty complicated, isn't it? This is how it is used mostly, but overall you can manage pretty well without using 'zouden'. It is really a verbal form that you should be able to recognise, but not necessarily use. There are lots of ways to avoid using it: "Je zou meneer Janssen moeten bellen" - "Je kan het beste meneer Janssen bellen" "Jij zou toch ook naar dat feestje gaan?" - "Jij ging toch ook naar dat feestje?" "Zou ik hier mogen zitten?" - "Mag ik misschien hier zitten?" "Zou jij nou de eerste alinea schrijven of de tweede?" - "Ging jij nou de eerste alinea schrijven of de tweede?" (Very informal) "Dan zouden we de afspraak moeten verzetten" - "Dan moesten we de afspraak verzetten" "Zou je volgende week kunnen?" - "Kan je volgende week?"

In short: When you want to ask something in a polite manner, you might want to use 'zouden', yes. However, 'zouden' is not only used to be polite. In the first sentence you use 'zouden' to be more polite. "Zou ik een nieuwe..." instead of "kan ik een nieuwe..." In the second sentence you use 'zouden' to talk of a possibility. Something that might eventually happen or be so. Actually the differences are very difficult to notice or explain. I'll try to give an example. If you are making an appointment with your dentist, he might ask you "zou je volgende week maandag kunnen komen?" In this sentence he doesn't use 'zouden' to be polite, just because he is asking about a possibility. You could answer by saying "Nee, dan zou ik niet kunnen." (Note: you could also use 'kunnen', that would work just fine) Another example of speaking of a possibilty/imaginary situation: "Wat zou jij doen als je de loterij zou winnen?" An even more complicated situation in which you can use 'zouden' is when you speak of something that was supposed to be, or when something that was claimed or stated in the past is now contradicted, or... whatever, just take a look at the examples. When you are talking about a party next weekend, and you think your friend is going too, but you're not sure, you may ask him/her: "Jij zou toch ook naar dat feestje gaan?" Also often used is "Jij ging toch ook...." After the party, if a friend of yours didn't show up, while you thought he would, you can ask him/her: "Jij zou toch ook naar dat feestje gaan?" You use 'zouden' because he was supposed to go too, because he had told you before. When talking about some group work with your classmates you might ask "Zou jij nou de eerste alinea schrijven of de tweede?"

Eww, this is unreadable without any paragraphs or anything. I should post this somewhere else...