Predicates
The fundamental word in the predicate is the verb.
A verb is a word—or a word-group—the function of which is to assert something about the subject.
The tide rises.
The sun shone.
I bought a book.
The box is small.
The verb may consist of one word—as in the examples given—or it may consist of a group of words, called a verb-group, containing sometimes as many as five words. This verb group consists of one, two, three, or four auxiliary verbs, followed by a form of the verb expressing the meaning or sense. The form of the sense-verb is an infinitive, a present participle, or a past participle.
The moon will rise.
The moon is rising.
The moon has risen.
He may light the lamp.
He is going to light the lamp.
The lamp at last was lighted.
The lamp has been lighted.
The lamp may have been lighted.
He may have been going to light the lamp.