Questions & Answers about Mój brat nie jest inżynierem.
Why does the sentence use inżynierem instead of the dictionary word inżynier?
When we use the verb być (to be) to talk about someone's profession, nationality, or role, the noun that follows must be in the Instrumental case. Because of this rule, the base word inżynier (engineer) changes its ending and becomes inżynierem.
How do we know to add -em to make inżynierem?
For most masculine nouns that end in a consonant, you form the Instrumental case by simply adding -em. Since inżynier ends in the consonant 'r', it becomes inżynierem. Keep in mind that if the profession was a masculine noun ending in 'a', like dentysta, it would act like a feminine noun and become dentystą instead!
Does the word nie always go right before the verb?
Yes, in Polish, the word nie (not) must be placed directly in front of the verb it is negating. To say 'is not', you will always group them tightly together as nie jest.
Why do we use mój instead of moja for 'my'?
Mój is the masculine form of the word 'my'. Because brat (brother) is a masculine noun, the word describing it must match its gender. If you were talking about your sister, you would switch to the feminine form and say moja siostra.