The sentence is characterised by its specific category of predication. Predication establishes the relation of the named phenomena to actual life.
The general semantic category of modality is also defined by linguists as exposing the connection between the named objects and surrounding reality. However, modality, as different from predication, is not specifically confined to the sentence; this is a broader category revealed both in the grammatical elements of language and its lexical, purely nominative elements. Thus every word expressing a definite correlation between the named substance and objective reality should be recognised as modal namely:
1) lexemes of full notional standing (as probability, desirability, necessity etc) with all the derivationally relevant words;
2) semi-functional words and phrases of probability and existential evaluation (perhaps, may be, by all means, etc.);
3) word-particles of specifying modal semantics (just, even, would-be, etc.);
4) modal verbs expressing a range of modal meanings.
Predication proper embodies not any kind of modality, but only syntactic modality as the fundamental distinguishing feature of the sentence. It is the feature of predication, fully and explicitly expressed by a contextually relevant grammatical complex, that identifies the sentence in distinction to any other combination of words having a situational referent.
The centre of predication in a sentence of verbal type (the predominant type of sentence-structure in English) is a finite verb. The finite verb expresses essential predicative meanings by its categorial forms (primarily the categories of tense and mood). However predication is effected not only by the forms of the finite verb, but also by all the other forms and elements of the sentence establishing the connection between the named objects and reality (intonation, word order, different functional words). Besides the purely verbal categories, in the predicative semantics are included such syntactic sentence meanings as purposes of communication (declaration — interrogation — inducement), modal probability, affirmation and negation.