§ 112. Subject and Predicate.—The Subject, if separately expressed, must be a Noun or some word used as such, that is, a Pronoun, an Adjective used Substantivally, or a Verb in the Infinitive.
The Predicate is either expressed (together with connexion) by a Finite Verb, or else, as in 2 and 3, by an Adjective or a Noun or words which can be used in place of them.
Note that the third person Sing. & Plur. of a Verb cannot form a sentence by themselves, unless they are used in an Impersonal or an Indefinite sense (§ § 165, 166). Where they appear to do so, a subject is to be supplied from the context.
§ 113. Expanded Forms of the Simple Sentence.—In the foregoing sentences the Subject and the Predicate have been expressed by one word. But often several words are required to express them fully. In such cases the Subject or the Predicate is called Complex, and the added words are called Complements.
§ 114. Adjectival Complements or Attributes are added to Nouns to make their description complete, as vĭr bŏnŭs a good man, vĭr multārum virtūtum a man of many good-qualities.
Phrases consisting of a Preposition and a Noun are rarely used in Latin as Attributes. the man in the ditch is hŏmo quī in fossă est the man who is in the ditch.
§ 115. Substantival Complements.—Verbs often require the addition of some Noun or other word used Substantivally to complete their sense. Thus in Mārcŭs Gāĭō lĭbrum dōnăt Marcus presents a-book to-Gaius, lĭbrum is a Substantival complement to dōnăt, showing what Marcus presents, and G{subst:a-}}ĭō one showing to whom he presents it.
lĭbrum is called the Direct Object and Gāĭō the Indirect Object of dōnăt.
Other Complements are seen in prŏfĭciscāmŭr dŏmum
