Can someone explain to me the grammatical rule for:

  1. I thought he knew it
  2. I saw him arrive

Why use past tense (knew) for one,and present for another (arrive)

1 Answer 1


The verb in the second sentence is "saw", which has the past tense verb "saw". "him arrive" is a clause with an infinitive, which is unconjugated, that is, it is not present tense. The first example is not comparable, because it has a separate past tense clause "he knew it", which is the direct object of "thought".

  • Note that the subordinate clause in the first one is a "that" clause (which always has a finite (tensed) verb), even though the "that" may be omitted. I thought that he knew it would be equally good. The second one, with an infinitive clause cannot have "that".
    – Colin Fine
    Dec 9, 2022 at 16:12

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