Χαίρετε!
That sentence reads:
Παλαιὸς ὁ οἶνος χρηστός
Now, if I understood the Grammar correctly, an adjective without an article makes a sentence even if εστι is not present, as it can be seen in the 5th sentence of the same exercise:
Ὁ παλαιὸς οἶνος χρηστός (The old wine is good.)
But neither Παλαιός nor χρηστός bear the article, but only the noun ὁ οἶνος. How should I understand that?
Ἒρρωσθε!