An infinitive is to plus a verb form. It can be used as an adverb. Examples: to be, to see, to be seen, to be eaten.
Adverb infinitives are used to modify verbs. They usually tell why. Adverb infinitives are used to modify predicate adjectives. They may also be compound.
An infinitive phrase is made up of an infinitive and any complements (direct objects, predicate nominatives, predicate adjectives, or modifiers.) An infinitive phrase that comes at the beginning of the sentence is always followed by a comma and modifies the subject of the sentence.
Instructions: Find the infinitive phrases in these sentences and tell what word they modify.
1. The actors performed there to entertain and to be seen.
2. The amount of danger was impossible to imagine or to describe.
3. I have come to ask a favor and to seek your help.
4. Are you unable to see or to read the sign?
5. The bucking horse jumped high to throw me and to break my neck.
–For answers scroll down.
1. to entertain/to be seen modify the verb performed
2. to imagine/to describe modify the predicate adjective impossible
3. to ask a favor/to seek your help modify the verb have come
4. to see/to read the sign modify the predicate adjective unable
5. to throw me/to break my neck modify the verb jumped
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from Daily Grammar Lessons Blog http://dailygrammarlessons.blogspot.com/2017/07/lesson-234-parts-of-sentence-verbals.html