Sie arbeiten in einem Büro - Name the Case?
So i'm trying to break down this sentence, and I'm a little stick on the use of "einem" - I've figured this is because "das Büro" is in the Dative case.. but why is this?
My only guess was that "They" were the object receiving the verbs action (in this case "arbeiten") ie. THEY work, resulting in "They" being in the accusative, making büro the dative.
am I correct?
Distinguishing the cases can be so hard sometimes, so thank you in advance for saving me!
In German, every preposition "governs" a grammatical case (which is often accusative or dative, sometimes genitive, but never nominative), which means that any noun coming right after that preposition has to be in a specific case. In the case of "in", that case is the dative, so "einem Büro" is in the dative case not because it recieves the action but because the preposition before it "commands" it to be in the dative case.
Note that in is a so-called "two-way preposition" which means it governs the dative case when expressing stillness (i.e. being at a place as opposed to moving towards/away from it), and the accusative when expressing motion towards it (= into).
For instance, you say:
-Ich bin in dem Büro. I am in the office (dative required) (note that "in dem" is often shortened to "im")
-Ich gehe in das Büro. i go into the office (accusative required) ("in das" is often shortened to "ins")
As for the case of "sie" in "sie arbeiten", there is actually an easy way to tell whether its nominative or accusative based on the English translation, because many pronouns in English kept a nominative case separate from the accusative:
(nominative - accusative or dative)
I - me
he - him
she - her
we - us
they - them
So when you see "they", you know it is the nominative case, and not the accusative or dative which would be translated as "them"
Preposition "in" comes either with either accusative or dative. Accusative is about the direction. Dative is about the location.
Ich gehe in das Haus. I am walking into the house (Im entering it from outside) Ich gehe in dem Haus. I am walking in the house (Im walking somewhere in the house).
It is no dative object, its an adverbial construct (auf Deutsch: Adverbiale Bestimmung).
Now since the action "arbeiten" is happening in the Büro, you use this dative phrase. You try to state location and thats the reason for this construction.
First of all, 'sie' is in the nominative case. The reason for this is it is the subject of the sentence, that is 'they' are the people that are doing the action, which is working. "Sie arbeiten..." - "They are working", they are the ones doing the work.
Next Büro is a neuter noun. In this instance, it takes the dative place because there is no movement involved. They were only working in one office/within that same office.
Since Büro we are talking only about some office in general and not a specific one, we will use the indefinite neuter article in the dative case which is einem. Hence, "in einem Büro".
Note: 'in' is a two-way preposition so it can take accusative or dative depending on context. If there is movement involved, then it would be the accusative case.
For example, "I am going to the Cinema." would be "Ich gehe ins Kino." Ins is a contracted form as many prepositions are often contracted when used with definite articles; in this case it is: in+das = ins (Kino is neuter).
You can tell whether 'sie' is accusative or nominative as the function of the accusative case is to mark direct objects, that is objects that receive the action e.g. "Ich esse den Apfel". what is being eaten? The apple.
In English, we have do not really have a case system but we do have objective, subjective and possessive pronouns. If sie is being used in the accusative case, it would translate to the English pronoun of 'them'.
In summary, here is the function of the four cases (excluding prepositions):
Nominative - subject(s) of a sentence - thing(s) that do the action
Accusative - direct object(s) - thing(s) that receive the action
Dative - indirect object(s) - thing(s) that benefit from an action (for instance, who receives the object that you are giving or who receives the help). Generally you can tell if something is an indirect object if you add 'to' in front of it in English and it makes sense, for instance, "I help you" - "I give help TO you" - "Ich helfe dir"
Genitive - Possession - Shows possession similar to 's in English. In colloquial German, a suitable replacement is using the preposition VON + Dative similar to using 'of' in English.
For instance: Das Auto des Mannes ist schnell. ("The man's car is fast") - Genitive Das Auto vom Mann ist schnell (Literally - The car of the man is fast) - 'dative possession'
Also in colloquial German, some prepositions that normally take genitive are replaced with the dative case. However, you should NEVER do this in written German - es ist verboten!