σοφός belongs to the first and second declension, if I'm right. How can an adjective belong to both the first and the second declension at the same time?
Does Greek grammar make a distinction between futurum exactum and futurum simplex?
the adjective σοφός belongs to the first and second declension simply because it is an adjective of three endings: -ος, -η (or -α), -ον, i.e. σοφός, σοφή, σοφόν and thus the masculine (σοφός) and the neuter (σοφόν) are declined according to the second declension, while the feminine (σοφή) is declined according to the first declension.
In ancient Greek, in fact, there are adjectives of the so-called “vowel declension” as their stem ends in vowel, like e.g. σοφός (whose stem is σοφο-), and adjectives of the so called “consonant declension” as their stem ends in consonant like e.g. ἀληθής (whose stem is ἀληθες-).
That being stated, note that among the adjectives of the so-called “vowel declension” there are:
1)Adjectives of Three Endings, like e.g. σοφός, σοφή, σοφόν or ἄξιος, ἀξία, ἄξιον; these adjectives belong to the first and second declension.
2)Adjectives of Two Endings, like e.g. ἄδικος, ἄδικον, that use the ending -ος for the masculine and the feminine, while the ending –ον is for the neuter; these adjectives belong to the second declension only;
Similarly, among the adjectives of the so-called “consonant declension” there are:
1)Adjectives of Three Endings, like e.g. μέλας, μέλαινα, μέλαν (stem: μέλαν) which in the masculine and neuter are declined according to the 3rd declension, while in the feminine belongs to the 1st declension.
2)Adjectives of Two Endings, like e.g. ἀληθής, ἀληθές (stem: ἀληθες) or ἄχαρις (stem : αχαριτ), ἄχαρι, which are declined according to the 3rd declension, as ἀληθής and ἄχαρις are both masculine and feminine, while ἀληθές and ἄχαρι are neuter.
3)Adjectives of One Ending, like e.g. ἅρπαξ (stem: αρπαγ) which have the same termination for masculine, feminine and neuter.They are declined according to the 3rd.declension only.
As for the futurum exactum (future perfect) and the futurum simplex (future simple), ancient Greek grammar makes a distinction either in their formation or in their meaning, but the futurum exactum is quite rare.
For example, the future simplex, indicative mood, active form, of the verb γράφω is γράψω (I will/I shall write) denoting an action that will take place at some future time, while the futurum exactum, indicative mood, active form, of the same verb, is γεγραφώς ἔσομαι (“I will have written" or "I am going to have written” ) denoting a future state resulting from a complete action.
As you can see, the future simplex γράψω ( indicative mood, active form) ,is different from the periphrastic form γεγραφώς ἔσομαι composed of the perfect participle γεγραφώς and ἔσομαι which is the future of the verb εἰμί (I am).
Hope this can be helpful to you.