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Words "leave" and "arrive" belong to which part of speech (noun or bare infinitive) in the following sentences:

We saw Fred leave.

Did you hear them arrive?

marked as duplicate by snailboat Feb 2 '18 at 23:25

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    Both leave and arrive are verb. They are part of a subordinate non-finite clause. We call it infinitive clause. An infinitive clause is generally introduced by a subordinator to (we often call it infinitive marker). But here it's grammatical to omit the infinitive marker, we call it bare-infinitive clause. few verbs like see, hear etc licenses bare infinitive clause. – Man_From_India Mar 4 '17 at 16:09
  • Thank you Man_From_India. @snailplane adds verbs-of-perception tag and I googled that tag and find englishgrammar.org/verbs-perception. now my question is this structure is unique to the verbs of perceptions? – tuxestan Mar 4 '17 at 16:11
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    Verbs of perception generally licenses bare infinitive clauses. Notice that in your example sentences the verbs of your matrix clauses are saw and hear. They both are verb of perception. They expresses "perception". – Man_From_India Mar 4 '17 at 16:17
  • ell.stackexchange.com/questions/37060/… There's a good answer here. – V.V. Mar 4 '17 at 16:42
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    They are both bare infinitival verbs. "See" and "hear" are catenative verbs, and "leave" and "arrive" are non-finite clauses function as their catenative complements. – BillJ Mar 4 '17 at 18:15

You are asking for the part of speech. They are all verbs functioning as catenative verbs.

Verbs of perception are idiosyncratic in that they can take a bare-infinitival clause as a complement. So both sentences are fine.

Additional information

  1. Causative-let and -make take only a bare infinitival complement.

He made me cry.OK

He made me to cry.not OK

However, make requires a to-infinival complement when it's passive.

He was made to repeat the whole story.

  1. "to help" can take either to-infinitive or bare-infinitive. The to-infinitive version is rather formal and quite common in British English:

That helps (to) propel me to victory.

  • Yes, though make takes a to-infinitival complement when it's passive. – snailboat Feb 2 '18 at 23:20

We saw Fred leave.

Did you hear them arrive?

These are both catenative constructions.

"See" and "hear" are catenative verbs, and "leave" and "arrive" are bare infinitival non-finite clauses functioning as catenative complements. The intervening objects "Fred" and "them" belong syntactically in the matrix clauses, not the infinitivals, though they are, of course, understood as the subjects of the latter.

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    If only there was an English translation of this answer for non-linguists, I might have a clue as to what any of this means. I'm a native speaker and have to wonder whether this can mean more to English language learners than it does to me. Just sayin'. – fixer1234 Mar 5 '17 at 1:24

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