Noun clause used as object of preposition S=subject in the main clause/P=predicate in the main clause/ s'=subject in the dependent clause/p'=predicate in the dependent clause/ prep.=preposition /  obj. of prep.=object of preposition / sub.conj.= subordinate conjunction /rel.pro.= relative pronoun 
1. I know nothing about the matter except what Alice told me late last night. 
2.

I know nothing except that she was found dead.

3.

Men are different from brutes in that they can think and speak.

1.

I know nothing about the matter

except

 what Alice told me late last night.

  prep. obj. of prep.
=>
what
Alice
told me late last night.
rel.pro. s' p'

2.

I know nothing

except

 that she was found dead.

  prep. obj. of prep.
=>
that
she
was found dead.
sub.conj. s' p'

3.

Men are different from brutes

in

  that they can think and speak.

  prep. obj. of prep.
=>
that
they
can think and speak.
sub.conj. s' p'