Questions & Answers about Bogate kraje są bardzo ważne.
Why do the adjectives end in -e (bogate, ważne)?
In the nominative plural, Polish adjectives have two forms: one for groups including at least one male person (virile) and one for everything else (non-virile). Since kraje (countries) are things, not men, we use the non-virile forms bogate and ważne. The virile forms would be bogaci and ważni.
Is kraje considered a non-virile noun?
Yes! The singular form is kraj (country), which is a masculine inanimate noun. Because it isn't a male person, it falls into the non-virile category when pluralized. That is why it forces the adjectives to use the non-virile -e ending.
The singular is kraj. Why does the plural end in -e instead of -y or -i?
Masculine inanimate nouns that end in a soft consonant sound, like the j in kraj, typically take an -e ending to form the plural.
Wait, don't neuter singular adjectives also end in -e?
Good catch! Yes, bogate and ważne look exactly the same as the neuter singular forms (like in bogate dziecko - a rich child). You know they are plural here because they are describing kraje (a plural noun) and are used with the plural verb są (are).