Verbs at the end of the sentence
I've not fully got my head around this matter. But when the second verb goes to the end it was my understanding that is takes it full form such as..." ich kann dich nicht verstehen" and not to be "verstehe". But I know this is not always the case. What makes the verb change to its full form or not when it goes at the end of the sentence?
Subordinate clauses kick the finite verb to the end of the clause. For example, "If I see you at the cinema" = "Wenn ich dich im Kino sehe..." A subordinate clause can come at the end of a sentence. For example, "I will be happy if I see you at the movies" = "Ich werde glücklich sein, wenn ich dich im Kino sehe." Relative clauses are a type of subordinate clause and so they also kick the finite verb to the end of the clause. The woman, who wears the red dress... = Die Frau, die ein rotes Kleid trägt...
Hope that helped.
There are a few reasons there could be a verb at the end. Understanding which situation causes the verb to go to the end will not only help you know which form of the verb to use, but help you understand the meaning of the sentence.
- It's just a short sentence:
Ich verstehe! = "I understand!"
Here it's just a totally normal sentence with the conjugated verb (the one that is modified to match the subject) in the second position, but there are no more words in the sentence.
- It's a subordinate clause:
Ich verstehe, weil ich schlau bin = "I understand because I am clever"
Subordinate clauses are like sub-sentences, and they cause the conjugated verb to go to the end. There are many different types of subordinate clauses in German but they all have the same effect on verb position.
- There's another verb:
Ich kann es verstehen = "I can understand it"
This is quite a common pattern that you will see - when a second verb is involved, only one of them is conjugated and in the usual second position. What happens to the other one? In German it often goes to the end in a kind of 'neutral' form called the infinitive. This is the 'dictionary form' of the verb, not conjugated or modified in any way. English also has infinitives if you think about it.
I think the first time you learn this pattern it is for modal verbs like können, müssen, sollen, wollen but it also shows up in other constructions using another verb:
Ich sehe ihn laufen = "I see him running"
Ich werde sie anrufen = "I will call her"
- It's got a helping verb:
Ich habe es verstanden = "I have understood it"
This is also common to see, and like with the previous example only one verb is conjugated and in the second position. But the verb at the end has a different form here, called the (past) participle. Along with memorising the infinitive and conjugated forms of a verb, you also need to remember its participle! It is used, as in this example, for talking in the past tense. English also has participles.
The participle is also used in the passive voice:
Das Brot wird gegessen = "The bread gets eaten"
Later, you can combine all these structures with other elements and each other to express whatever you want to. By then your German will be pretty good!
I would say no, you are not right in saying that, apart from situations where the passive voice is used (i.e. „Das Brot wird gegessen“), or there are separate clauses (i.e. „Ich verstehe, weil ich schlau bin“).
Otherwise, the second verb in a present tense clause always has to be in its infinitive form (wenn ich mich nicht irre).
With full form you mean infinite form (gehen, wollen,haben)? For main clauses, you'll always have one finite verb (will,gehst, hat) at the second position and one or several infinite forms or participles (gegangen, gewollt, gehabt) in the end of the sentence (Ich habe es nicht verstehen können). In subordinate clauses you'll find the finite verb in the end (..., dass ich es nicht verstehen konnte).
You can have sentences with a "Modalverb" or "Hilfsverb" like dürfen, können, mögen, müssen, sollen, wollen or möchten and another verb, the "Vollverb". In this case the Vollverb is in Infinitiv.
This is the case in your example: "ich kann dich nicht verstehen" (I can't understand you)
Here we have können as a Hilfsverb. It gets conjugated, to 'help out' the Vollverb - which in turn stays in the infinitive form.
You can also have sentences with 2 verbs when you are talking in Perfekt, Plusquamperfekt or Futur I/II tense. In this case the Vollverb will be in Partizip II (e.g. "ich habe dich nicht verstanden" is a sentence in the Perfekt tense).
(I hope this is somehow clear. I have no experience explaining these things.)