German verbs are conjugated depending on their use: as in English, they are modified depending on the persons (identity) and number of the subject of a sentence, as well as depending on the tense and mood.
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The citation form of German verbs is the infinitive form, which generally consists of the bare form of the verb with -(e)n added to the end. To conjugate regular verbs, this is removed and replaced with alternative endings: Radical: mach-
- To do; machen
- I do; ich mache
- He does; er macht
- I did; ich machte
- He did; er machte
In general, irregular forms of German verbs exist to make for easier and clearer pronunciation, with a vowel sound in the centre of the word the only part of the word that changes in an unexpected way (though endings may also be slightly different). This modification is often a moving of the vowel sound to one pronounced further forward in the mouth. This process is called the Germanic umlaut. However, a number of verbs including sein (to be) are fully irregular, as in English I am and I was sound completely different.
- To know; wissen Radical: wiss- wuss-
- I know; ich weiß or weiss (vowel change; -e missing) (irregular)
- I knew; ich wusste (vowel change; otherwise regular)
- To sing; singen
- I sing; ich singe (regular)
- I sang; ich sang (vowel change; -te missing)
For many German tenses, the verb itself is locked in a non-varying form of the infinitive or past participle (which normally starts with ge-) that is the same regardless of the subject, and then joined to an auxiliary verb that is conjugated. This is similar to English grammar, though the primary verb is normally placed at the end of the clause. Note that in both the examples shown below the auxiliary verb is irregular.
- I buy the book; Ich kaufe das Buch.
- I will buy the book; Ich werde das Buch kaufen.
- She will buy the book; Sie wird das Buch kaufen.
- I have bought the book; Ich habe das Buch gekauft.
- She has bought the book; Sie hat das Buch gekauft.
The following tenses and modi are formed by direct conjugation of the verb:
- Present – Präsens
- Imperfect – Imperfekt or Präteritum
- Imperative – Imperativ
- Perfect – Perfekt (past participle, does not vary by subject)
- Conditional I and II – Konjunktiv