[Grammar] 'I heard her scream..' versus 'Claire was seen to leave the house before midnight'

[JarekSteliga]

1. 'I heard her scream twice last night'

2. 'Claire was seen to leave the house before midnight'


I came across these two sentences in close succession in an English test.


When I read the first one, I thought 'scream' was a verb. Seeing how a verb in infinitive 'to leave' is used in a similar structure (or at least what I consider to be a simililar structure), I am now beginning to think that 'scream' in the first sentence was a noun, not a verb.

Is 'scream' a nound in the first sentence?

If not, how to account for the fact that bare infinitive is used in the first sentence while a full infinitive is used in the second?

 

[5jj]

1. 'I heard her scream twice last night'
or: "She was heard to scream twice last night." This is not very natural, but it's possible.

2. 'Claire was seen to leave the house before midnight'
"I saw Claire leave the house before midnight"

[...] If not, how [STRIKE]to[/STRIKE] can/do we account for the fact that bare infinitive is used in the first sentence while a full infinitive is used in the second?

We use different constructions for the active and passive.