Infinitive used as modifier can have a passive meaning:

the bench is too wet to sit on

  • "this bench can't be sat on"

The action "sit" is directed at the subject as if it were in passive voice although it is not in passive voice. The action can also be directed at the first object: I need a couch to sleep on - "sleeping" is directed at "couch". I am also interested in this usage.

I am trying to find if this meaning is always possible to create or there any limits to it. From what I understand, in each of my examples the infinitive is directed either at the subject or first object of the sentence. Are they correct and idiomatic?

He is too weak to talk to

She has 3 friends to talk to

She is difficult to lie to

I need a private jet to go on business trips on

He is the best man to borrow money from

He is too poor to spend money on ("we shouldn't spend money on him")

The company is too unstable to invest in ("we shouldn't invest in this company")

One more crucially important question:

He is too young to kill

Can be interpreted both ways:

We can't kill HIM because he is too young


HE can't kill (people), because he is too young

Is that correct that this sentence can be used/interpreted in both ways?

  • 1
    I don't know why this was downvoted. It's an extremely good question which, even as a native English speaker, I haven't got a clue as to how to answer it. Jun 9, 2022 at 11:08
  • Thank you for your support, could you tell me which of the sentences that I provided, sound natural and correct and which don't? Jun 9, 2022 at 11:12
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    They all come across as basically grammatically correct and natural, except perhaps I might say "I need a private jet for business trips". Unfortunately I am unable to explain exactly why this construction uses the active and not the passive voice. It's just the way it is. Jun 9, 2022 at 11:17
  • No worries, you've already helped me a lot by confirming most of these are natural and correct. Passive meaning in these sentences comes from the fact that this usage of infinitive substitues a that-clause e.g. I need a couch to sleep on = I need a couch (of which kind?) that I can sleep on. And these clauses naturally direct the action in the second sentence to the object/subject of the first sentence. (in semantic sense). At least that's what I think about this usage. Jun 9, 2022 at 11:28
  • @PrimeMover I've updated my post, could you please clarify if my understanding of the last sentence I added is correct ("He is too young to kill") Jun 9, 2022 at 12:58

1 Answer 1

  1. All of your examples are correct except for the fourth one:

I need a private jet to go on business trips on with

  1. Yes, the sentence

He is too young to kill.

is ambiguous. It's not clear if he's too young to be a killer or he's too young to be killed.

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