[Grammar] how to recognize infinitive as adjective and adverb

[satya_sson33]

:?: i brought a knife to cut vegitable with .
In above given sentence, infinitive as adjective or adverb. why do we use preposition after infinitive like with is used in above sentence.i have a confusion above given sentence that it is modifying both (knife and brought).so, sir please explain me how to identify infinitive as adjective or adverb.

 

[susiedqq]

I bought a knife to cut the vegetables.

 

[corum]

I brought a knife to cut vegetables with. :tick:

In your sentence, the string of words after 'brought', a noun phrase with 'knife' being the head, serves as the direct object of 'brought'. This part does not modify, but complements the verb.

a knife to cut vegetables with = a knife with which I can cut vegetables

The infinitive verb phrase (this is the formal definition of "to cut vegetables with") functions as a postmodifier of 'a knife' (not simply 'knife'). It is an adjectival relative clause in function. You have problem with the stranded preposition, right? It is okay there. It is related to 'a knife'.

I brought a knife to cut vegetables [STRIKE]with[/STRIKE]. :tick:

Different meaning. Here, the infinitive verb phrase provides the reason for your having brought a knife. Reason clause, adverbial.

---

I bought a mattress to sleep on = I bought it so that I have something to sleep on.

I bought a mattress to sleep [STRIKE]on[/STRIKE]. = ?
I bought it for sleeping.

how to recognize infinitive as adjective and adverb?

Ask yourself the question: What does the sentence mean? :up:

 

[satya_sson33]

I brought a knife to cut vegetables with. :tick:

In your sentence, the string of words after 'brought', a noun phrase with 'knife' being the head, serves as the direct object of 'brought'. This part does not modify, but complements the verb.

a knife to cut vegetables with = a knife with which I can cut vegetables

The infinitive verb phrase (this is the formal definition of "to cut vegetables with") functions as a postmodifier of 'a knife' (not simply 'knife'). It is an adjectival relative clause in function. You have problem with the stranded preposition, right? It is okay there. It is related to 'a knife'.

I brought a knife to cut vegetables [STRIKE]with[/STRIKE]. :tick:

Different meaning. Here, the infinitive verb phrase provides the reason for your having brought a knife. Reason clause, adverbial.

---

I bought a mattress to sleep on = I bought it so that I have something to sleep on.

I bought a mattress to sleep [STRIKE]on[/STRIKE]. = ?
I bought it for sleeping.



Ask yourself the question: What does the sentence mean? :up:

sir, infinitive as adverb has same subject as sentence has or different.

 

[corum]

I can't think of an example where they are not the same.

I brought a knife to cut vegetables = I brought; I cut

 

[satya_sson33]

I can't think of an example where they are not the same.

I brought a knife to cut vegetables = I brought; I cut

# he paid you $50 to cross the river.

i have a confusion in that sentence that infinitive has different subject and it is as adverb but sir, when infinitive works like adverb then it has same subject. it used as a adverbial phrase that means 'the purpose of the subject'?

he paid you $50 = why did he paid you?.......... to cross the river

 

[corum]

# he paid you $50 to cross the river.

when infinitive works like adverb then it has same subject.

It is not necessarily true as you can see from your example.