Strong and Weak Verbs

Have you come across the phrase “strong verbs” or “weak verbs” in your studies and wondered what exactly is meant?  

Strong verbs have a stem-vowel change in one or more tenses, for example in the simple past or present tense. In other words, they are irregular. The sign of a strong verb is that its participle will end with -en.

For example, with genießen ("to enjoy") the present tense conjugations do not have a vowel change, but the past tense does (genoss). The participle accordingly ends with
-en:

Genießt euren Kaffee, wie auch immer ihr den zubereitet.

Enjoy your coffee, regardless of how you make it.

Caption 39, Eva zeigt uns - wie man Kaffee kocht
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Und ich habe an einer sehr renommierten Universität ein sehr umfangreiches Marketingstudium genossen.

And I enjoyed a very comprehensive marketing program at a very renowned university.

Captions 26-27, Berufsleben - das Vorstellungsgespräch - Part 2
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In the case of the verb empfehlen (“to recommend”), the present and simple past tenses both have a different stem vowel change. Once again, the participle ends with -en:

Neben dem Stadtrad empfiehlt sich vor allem die Innsbruck Card für die Erkundung.

In addition to the city bike, above all, the Innsbruck card can be recommended for the exploration.

Captions 26-27, 48 h in Innsbruck - Sehenswürdigkeiten & Tipps
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Schafft das keine Linderung, wird empfohlen, die Höhe des Computerbildschirms zu überprüfen.

[If] that doesn't bring relief, it's recommended [that you] check the height of the computer screen.

Captions 19-20, Nackenverspannungen - Entspannungstipps für den Büroalltag
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Weak verbs are more “regular” in the sense that all tenses resemble the infinitive. The participle ends with -t. Let’s look at the verb reisen:

Wenn man gemeinsam reist, ist es immer besser.

It's always better if you travel together.

Caption 20, Traumberuf - Windsurfer
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Dafür reiste das Filmteam bis nach Korsika.

For this the film team traveled as far away as Corsica.

Caption 35, Hell - Science-Fiction-Kinotipp
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Für zwei Wochen bin ich durchs Land gereist.

For two weeks, I traveled across the country.

Caption 20, Grete - eine Freiwillige in Israel
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Now, of course, because German is never easy, there are exceptions in the form of irregular weak verbs. These have a participle with -t rather than -en, but also have a stem vowel change. Many common verbs, such as bringen and wissen, fall into this category.

Ein Benefiz-Fußballspiel brachte sie jedoch alle zusammen auf den Rasen.

A benefit football match nevertheless brought them all together on the turf.

Caption 2, Fußball - Prominente beim Benefizspiel
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Aschenputtel wurde in den Palast gebracht.

Cinderella was brought to the palace.

Caption 105, Märchen - Sagenhaft - Aschenputtel
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Further Learning
When you learn a new verb on Yabla German, always find out immediately whether it's strong or weak and memorize this as well as its definition. Here is an extensive list of strong and irregular verbs. Look up the participles of niesen versus genießen and of the verbs winken and stinken, which are particularly tricky.