Can the German Nebensatz be put in the middle of the sentence?

Question

I once asked a question if the sentence > jeder muss dafür verantwortlich sein, was er gesagt hat is correct and was told that it is acceptable and that the verb must go at the end of its own clause before any subordinate clause. However, I was also told by a native speaker that this sentence could also be enclosed by one, like > Jeder muss für das, was er gesagt hat, verantwortlich sein. or > Jeder ist für das, was er gesagt hat, verantwortlich. I just wonder that in the first sentence above the verb 'sein' goes to the end of the entire sentence after the subordinate clause. It really annoys me how should I correctly build the German main clause and subordinate clause and is there a rule I can follow? And Take the following sentences. > 1. Sobald ich Zeit habe, werde ich dir helfen. > 2. Ich werde dir helfen, sobald ich Zeit habe. > 3. Ich werde dir, sobald ich Zeit habe, helfen. I can understand the first two sentences well but I still get confused by the third one.

Answer 1

In fact, all of your three variations at the end are grammatically correct. However, the third would only be used if the speaker would want to make a very poignant case of ONLY helping if/when there is time (fairly impolite).

As for the sentence "jeder muss, für das was er sagt, verantwortlich sein", the order of the words comes from the collision of multiple constructs and each of their respective rules.

Let's walk through this...

If we split the sentence up into basic present tense statements we get:

1. Jeder ist verantwortlich.
2. Er sagt etwas.

The first statement now gets the modal "müssen". The rule of modals says the modal gets conjugated and the operative verb moves to the end of the sentence, changing into its infinitive form.

1. Jeder muss verantwortlich sein.

Now you add a prepositional clause, using the second statement. The rule for prepositional clauses says they need to start after the verb. Here we have the choice of two: The modal and the operative verb - either is fine. Additionally, we change the statement slightly to include the "that which" ("das was"). .

1. Jeder muss, für das was er sagt, verantwortlich sein.
2. Jeder muss verantwortlich sein, für das was er sagt.

Another point is that helper verb constructs (Perfekt, Futur, Modal, etc.) are so-call "Satzklammern" (sentence brackets), i.e. they "surround" the rest of the sentence. What they surround can be either just one or more object groups ([article] & [adjective] & object) or, as it the case here, an entire clause.

HTH