I came across this sentence somewhere:

This dictionary took three years to complete.

Clearly, it means '[...] took three years to be completed'.
Is this sentence correct? And if so, how can the use of non-passive voice be explained? I looked in several dictionaries but I couldn't find an intransitive form for 'complete'. Is 'complete' an ergative verb?
Which form is more common?

  • You should think of this sentence as being This dictionary took three years for us/them/him to complete, with for us/them/him left out. Jan 6, 2021 at 22:40
  • @PeterShor Is this sort of omission/ellipsis common in English? It indeed sounds better with the 'for them' added. But I was mostly comparing the sentence to something like "It took us three years to complete the dictionary" where the 'subject' of the 'to complete' infinitive is clearly us/we and its object is the dictionary, at least based on the meaning. Whereas the infinitive in the original sentence doesn't appear to have a object. Please correct me if I'm wrong; I'm not sure about this grammatical structure.
    – S_Celea
    Jan 6, 2021 at 22:56
  • Moreover, the fact that both passive and active voice appear to work in this sentence is confusing me. (Unless the passive form is wrong and I'm mistaken)
    – S_Celea
    Jan 6, 2021 at 23:06
  • A similar sentence is The game Monopoly requires infinite patience to play. The passive voice doesn't work here: The game Monopoly requires infinite patience to be played is not anything a native speaker would say. Jan 6, 2021 at 23:14
  • The object of the infinitive to complete in the original sentence is dictionary. Unfortunately, I don't know the technical term for this grammatical structure. Jan 6, 2021 at 23:20

1 Answer 1


In the sentence

This dictionary took three years to complete.

'To complete' is not functioning as an intransitive verb; rather, the structure used is a nonfinite relative clause with the logical subject of the sentence acting as the object of the infinitive clause, while the subject of the clause remains unspecified, forming a passive-like structure. Another example of such a construction is

Cancer prevention is a common topic to talk about in these circles.

where the people talking about the topic is left unspecified, but the implied object of the clause is cancer prevention.

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