Questions & Answers about Mój brat i jego żona dobrze się rozumieją.
Because brat is a masculine singular noun, and mój must agree with it.
- mój = my (for masculine singular nouns)
- moja = my (for feminine singular nouns)
- moje = my (for neuter singular nouns)
So:
- mój brat = my brother
- moja siostra = my sister
- moje dziecko = my child
In this sentence, brat is masculine, so mój is the correct form.
They are both in the nominative case, because together they form the subject of the sentence.
- mój brat = my brother
- jego żona = his wife
Since the sentence is about what they do, both nouns stay in nominative:
- Mój brat i jego żona = My brother and his wife
Even though there are two nouns, each one is singular on its own; together they make a plural subject.