1. He gave us a signal to move forward.

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What is the relationship between 'signal' and 'to move forward'?
Are they in apposition? Or does 'to move forward' modify 'signal'?

Yes, they are in apposition.

"signal" is the direct object of the verb "gave" and "to move forward" is an infinitive phrase being used as an appositive for "signal."

I respectfully disagree. "to move" is, I think, a prepositional phrase used to modify "signal". "forward" modifies "move". It would be an appositive if the sentence was written: "The signal, to move forward, was given by the lieutenant." An appositive is an adjective or adjective phrase of description, set off by commas. "Glenda, fair and graceful, was the good witch." or "Glenda, of the East, was a good witch."

Sorry, Reed, but Writeacher is correct. Since "move" is a verb, not a noun, "to move" is an infinitive.

Ahh -- we old English teachers may have limited knowledge -- but we do know infinitives from prepositional phrases.

In the sentence, "He gave us a signal to move forward," 'signal' and 'to move forward' are not in apposition; instead, 'to move forward' modifies 'signal'.

To understand the relationship between the two, let's break down the sentence:

- 'He' is the subject of the sentence, the person who performed the action.
- 'gave' is the verb, indicating the action performed by 'He'.
- 'us' is the object of the verb, representing the recipients of the action.
- 'a signal' is the direct object of the verb 'gave', receiving the action from 'He'.

Now, let's consider 'to move forward':

- 'to move forward' is an infinitive phrase, functioning as an adverbial modifier in this sentence.
- 'to move' is the infinitive verb form, representing the action of moving.
- 'forward' is an adverb, specifying the direction in which the movement should occur.

In this sentence, the 'signal' is given with the purpose or intention of indicating or instructing the recipients to move forward. Therefore, 'to move forward' modifies the 'signal', clarifying what the signal is intended to communicate.