German/Grammar/Prefixed verbs

Prefixed verbs
German loves to cobble together words from bits and pieces lying around. When verbs are created this way, something rather unusual can happen; the part that was added to the verb is not as fully attached as one might think, so it can detach itself, free to wander around the rest of the sentence. Where does it go?

Terminology
German has quite a few prefixes that attach to verbs. They can be divided into two types, separable and inseparable. Inseparable prefixes behave as you would expect them to, once they are attached to the root verb they stay attached and the verb is conjugated mostly as you would expect. One example is bekommen ("to receive") which is formed by adding the prefix be- to the the verb kommen ("to come"). In the future tense you use the infinitive: and in the present tense you conjugate normally: Note that while bekommen looks very similar to the English "become", they are very different in meaning. Verbs which are formed from a root verb and an inseparable prefix are called, as you would expect, inseparable verbs.
 * Ich werde das Geld bekommen. – "I'll receive the money."
 * Ich bekomme das Geld. – "I'm receiving the money."

Separable prefixes however, can detach themselves from the root verb. Consider: The verb in this sentence is anfangen ("to begin"), but it has split into fange, the finite part, and an, which is at the end of the sentence. Verbs which are formed from a root verb and a separable prefix are called, of course, separable verbs.
 * Ich fange meine Reise an. – "I'm beginning my trip."

Separable verbs correspond to what are called "particle verbs" in English. An example is "look up" as in "Which word did you want to look up." In this case the "up" cannot be interpreted as a preposition, which is its usual role, and is called a particle instead. English also has prepositional verbs similar to the German prepositional verbs we covered in the earlier section on prepositions. Collectively, English particle verbs and prepositional verbs are known as "phrasal verbs"; see English phrasal verbs in Wikipedia. Presumably, particle verbs and separable verbs evolved from the same feature of the ancient common ancestor of English and German. In English, the choice was made to keep the particle close to the verb but always separated, while in German, the particle was allowed to drift to the end of the sentence, but also to recombine with the root verb when circumstances allow.

Some prefixes, which we'll call variable, can either be separable or inseparable depending on the root verb. There are even a few verbs where the prefix can be separable or inseparable depending on the meaning. Such differences are usually due to the prefix having multiple meanings. For example über- can be from the preposition über meaning over as in physically above, or it can mean "over-" meaning too much, as in "I'm overworked." It's usually best to think of these different versions as different prefixes which happen to be spelled the same way. For example, either version of über- can be combined with setzen to produce two versions of the verb übersetzen. The inseparable version means "to translate", while the seperable version means "to cross over" (usually a body of water). Similarly umgehen means "to go around" or "to avoid" an obstacle as an inseparable verb, but it means "to circulate in/around" as a separable verb.

In spoken German, you can tell the difference between separable and inseparable prefixes because separable prefixes are stressed while inseparable prefixes are unstressed. There is no such distinction in the written language though.

Prefixed verbs follow the "Right Hand Rules" law when it comes to irregular conjugation. In other words, when a prefix is attached to an irregular verb then new verb is conjugated like the root verb, irregularities and all. But there are a few cases where a verb seems to be formed using a prefix but are actually not, and in these cases the verbs may be conjugated differenty. For example befehlen and empfehlen are related to each other through an extinct parent, but this parent is not the origin of fehlen. And in fact while fehlen is regular, the first two are stem-changing verbs.

Forming sentences with separable verbs
Forming sentences with separable verbs may seem odd to English speakers, but the process isn't to hard to understand once you get used to the idea. Recall that in the future tense, the helping verb, a conjugated form of werden, goes in the V2 position, while the infinitive of the main verb goes at the end. The general principle is that the finite part goes in the V2 position while the nonfinite part goes at the end of the clause. With separable verbs, you can think of the finite part as just the root verb, and the prefix as a nonfinite part. So, following the principle just mentioned, to use the verb anfangen, the fangen part is conjugated and placed in the V2 position, and the an part is placed at the end of the sentence. This is how we arrive at the previous example.

In the future tense, the verb is in the infinitive so the whole thing is nonfinite and goes at the end. For example: In this case, since both parts of the verb are in the same location, they do not separate and the verb looks like it would in a dictionary.
 * Ich werde meine Reise anfangen. – "I will begin my trip."

Understanding sentences with separable verbs
The biggest problem with understanding a sentence with a separable verb is recognizing that you're dealing with one. Remember that, with only a few exceptions, both the root verb and the prefix will be words in their own right. Also, the root is near the beginning of the clause and the prefix is at the end, and there can be a great deal of material in between, so there can be a large distance between to two parts of the verb; sometimes they are on different pages of a book. As relatively tame example is: As a learner who will be looking up a lot of verbs, you need to make sure there aren't any pieces at the end of the sentence which need to be added to the word you'll be looking up; knowing the meaning of the root verb is often little help in finding the meaning of the prefixed version that's actually being used.
 * Ich fange morgen meine Reise in die Vereinigten Staaten an. – "I'm starting my trip to the United States tomorrow."

Which prefixes are separable?
Grammarians have classified verb prefixes as separable, inseparable, or variable. We could give lists of each, but it's rather pointless to memorize this kind of thing when a simple rule of thumb works nearly as well. The rule is that prefixes that are words by themselves, usually prepositions or similar words, are nearly always separable, and prefixes that don't form words are nearly always inseparable. Some exceptions to make note of are dar-, which is not a word but is separable, and über- and um-, which are prepositions on their own but variable as prefixes.