Use of "für" with duration

Question

Duolingo has these sentences:

Ich kann meine Familie für ein paar Tage besuchen.

Wie viele Tage bleibst du in Deutschland?

which makes me wonder if für is ever used with "wie viele". Should I assume there is an implied and omitted für in the second sentence? I searched for "für wie viele" and found pages such as

Für wie viele Tage kann man eine seriöse Wettervorhersage machen? (source)

Für wie viele Tage kann der Arbeitnehmer zum Zwecke der Kinderbetreuung fernbleiben, wenn § 616 BGB zur Anwendung kommt? (source)

Für wie viele Tage bewahren Sie Site-Backups auf? (source)

What are the differences, if any, between these sentences and the versions without "für"?

Answer 1

The variant without für is a so called adverbial accusative. It marks a duration or a way taken. That alone is enough already.

That für is actually only for emphasis, or to avoid confusion with an accusative object.

Er hat (für) einen ganzen Monat geübt.

A month is not something that you can practice so this must be an adverbial accusative rather than an accusative object.

An alternative is appending über or lang

Er hat einen ganzen Monat (über/lang) geübt.

Answer 2

As @Janka mentions in her answer, adverbial modifiers of duration in German often do not employ the preposition that is equivalent to the English "for", but instead use an accusative noun phrase without the preposition. It is indeed rarer in English, but not non-existent: I can think of "The traffic was gridlocked the whole day".

English and German both have the two forms. German skews heavier towards the non-für form.

However, your last two examples indeed use "für". Yes, that is also acceptable.

I did not find mentions in the Duden grammar reference book about the prevalence of the two forms.¹ I did find a couple of pages on the internet that say "für" is mainly used for future durations.^{2 3}

As for your third-last example, I'd characterise the function of "für" as being related more to the tempus than the Aktionsart (lexical aspect — internal arrangement of time): "Für wie viele Tage kann man eine seriöse Wettervorhersage machen?" — The verb in this sense is telic. "For how many days" conveys the condition for which that forecast may be valid, not the duration of the activity of making the forecast.

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Sources

• ¹ Wöllstein, Angelika and Bibliographisches Institut, editors. Duden - Die Grammatik [Duden — Grammar]. 10th ed., Dudenverlag, 2022, pp. 208­−230.
• ² ‘Temporale Präpositionen’ [Temporal Prepositions]. mein-deutschbuch.de, https://mein-deutschbuch.de/temporale-praepositionen.html. Accessed 3 July 2024.
• ³ ‘Thema 23. Temporale Präpositionen’ [Topic 23. Temporal Prepositions]. IFU Sprachschulung, https://ifu-institut.at/online-lernen/grammatik/deutsch-grammatik-a1-thema-23. Accessed 3 July 2024.

Answer 3

I think that the "fűr" is inherited from the use in conjunction of trading/exchanging goods. Example: "Sie können diesen Wagen fűr zehntausend haben.” (You can have that car for 10,000) So the "fűr" indicates to invest time considered to be rare or precious into getting something like fun, education, business... in return.