Student or Learner
At the same time, we must recognize a relationship between their uses as conjunction and preposition. Compare:
With Mary I always feel happy.
Without Mary I always feel miserable.
I bought a car for Mary (so that she could drive to work in it).
(A Comprehensive Grammar of the English Language; Randolph Quirk)
Would you be so kind as to tell me whether with, without, and for function as prepositions in those sentences?
Quirk et al have some interesting things to say on this - for example, that with in "With Mary being away, John felt miserable", with functions as a subordinator, not a preposition. However, in the three sentences you quote, the italicised words are functioning as prepositions, in my opinion.