I have seen the following sentence:

They gave me a question too hard to answer.

However, in my opinion, this use of active infinitive is ungrammatical here, and the following passive Infinitive should be used here:

They gave me a question too hard to be answered.

I wonder which structure is more suitable for formal writing in case both structures are grammatically correct.

  • in my opinion, the first sentence is informal usage: "They gave me a question too hard (for me/anyone) to answer" May 16, 2021 at 14:58
  • 2
    I see no error in "too hard to answer".
    – James K
    May 16, 2021 at 15:32
  • 2
    I don't think there's anything "informal" about the first version. IMHO the second version is clumsy - looks like someone mistakenly trying to make the text formal, but it doesn't really work. May 16, 2021 at 17:52
  • @FumbleFingers So, according to your comment, is it always possible to replace a passive infinitive with an active one in similar situations? I ask you this question because, in my opinion, using the active infinitive in the example mentioned in the post is semantically incorrect.
    – Later
    May 17, 2021 at 13:56
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    I don't really see why you describe the situation as involving a need to replace a passive infinitive. There should be no concept of replacing the passive voice, because by default you shouldn't normally be using the passive voice in the first place. Start by using simple verb forms (including "active" rather that "passive" constructions), and only consider deviating from that if you really have to. There is nothing wrong with saying some question is too hard to answer - if you think that's "semantically incorrect", you're simply mistaken. May 17, 2021 at 14:12

2 Answers 2


Both are grammatical.

The second sounds stilted and awkward to me. That does not make it better for "formal writing", which should be clear and concise and avoid slang and contractions.


I would say “They asked me a question that was too hard to answer.”

  • Because the act of asking the question was in the past, so is the question. So, this is why you can say a “question that WAS too hard to answer”, since it isn’t being asked currently.
  • Thanks for this. You can improve your answer by explaining why this is better. Is the explicit relative clause "...that was" necessary? Why did you change "hard" to "difficult". Why don't you change "to answer" into "to be answered". When you have time, check How to Answer. And take care on spelling and punctuation. You're missing some capital letters in your answer.
    – James K
    May 16, 2021 at 15:41
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    Sorry about that James, it is my first time using this website and my device has autocapitalization turned off, so I forgot to add capital letters.
    – user136000
    May 16, 2021 at 15:55
  • @user136000 Thanks for your answer. However, I think the examples in the OP are grammatical and the main issue here is which voice of infinitive should be used.
    – Later
    May 17, 2021 at 9:59

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