Accusative or dative
New learners often confuse the accusative and dative cases in German. Misusing them frequently can cause serious confusion, and it sounds poor.
You can find the accusative noun in a sentence by asking the question "What is being ---ed?", where -â€“ed is replaced with the past perfect form of the active verb in the sentence.
If the active verb were "buy", you would ask, "What is being bought?" The answer is the accusative noun. You can find the dative noun by asking, "Who/what is getting something?" In the sentence "I bought my sister a house," the sister is the one getting something, and would therefore require dative case markers.
These questions require you to identify and use both the accusative and dative cases.