Questions & Answers about Ich merke das Buch vor.
Because vormerken is a separable verb.
The full verb is vormerken, but in a normal main clause, the prefix vor- separates and moves to the end:
- Ich merke das Buch vor.
In other forms, it stays together:
- infinitive: das Buch vormerken
- perfect participle: das Buch vorgemerkt
- subordinate clause: ..., weil ich das Buch vormerke
So vor is not acting as a preposition here. It is part of the verb.
Not really. In this sentence, you should treat vormerken as a separate vocabulary item.
- merken by itself often means to notice
- sich etwas merken means to remember something
- etwas vormerken means to reserve something, put it on hold, or note it down in advance
So you should not translate this sentence word-for-word as something like I notice the book ahead of time. The combined verb has its own meaning.