Learn Hardcore Russian: Море было спокойным и голубым.

In Russian, predicate adjectives that follow a past tense form of быть (to be) are typically set in the instrumental case to indicate a state or temporary quality of the subject. Since море is neuter, its descriptive adjectives take the neuter instrumental ending -ым to match in gender, number, and case.

How does the verb было function in this sentence?

Было is the past tense form of быть and serves as the linking verb, connecting the subject море to its descriptive attributes. In Russian, while the present tense of быть is usually omitted, the past (and future) tense requires an explicit form, making the state of море clear.

How do the adjectives agree with the noun море here?

The adjectives спокойным and голубым agree with море in gender (neuter), number (singular), and case (instrumental). This agreement is essential for ensuring that the descriptive words properly refer to the subject when used in a predicate construction with the linking verb было.

What role does the conjunction и play in this sentence?

The conjunction и connects the two adjectives, indicating that both спокойным and голубым describe the same subject, море. Its use signals that the adjectives are coordinated elements in the sentence, with no need for additional punctuation between them.

Could the adjectives have been used in a different form, such as in the nominative case?

While adjectives used attributively before a noun (as in спокойное голубое море) would appear in the nominative case, predicate adjectives in constructions with a past tense linking verb like было must be in the instrumental case to correctly express the state or condition of the subject.