First and foremost let me say a big 'thank you' to you for your outstanding and thorough answer.
[ I (Mav) in black (as night, black as cole :D ), Raymott in blue ]
If it were something like "He was strong enough (let's say it's a narrative) to have beaten up that rascal who had attacked his family a week ago (before the narrative point). Is it correct? Even if it is, it doesn't explain to me why Perf. Inf. is used in the sentence c. I
kind offeel it "weird" on its own, without further words, context, etc. like "He turned angry enough to have killed."
Goodness gracious! I've just realized that I used the wrong sentence here, in my original post. (I used the clipboard, i.e. Ctrl+C/Ctrl+V, and I inserted the wrong sentence after d). Of course I meant to write (or to have written ) d) "He had turned angry enough to have killed. I don't want to edit my post, but I'd like to point it out, along with my apologies for overlooking it.d) "He had turned angry enough to kill."
1.) He is believed to be drunk. (= Now they think he is drunk (now.))
2.) He was believed to be drunk. (Once they thought he was drunk then.)
3.) He is believed to have been drunk. (Now they think that once he was drunk.)
4.) He was believed to have been drunk. (Once they believed he had been drunk. Oh, my beloved Past Perfect.:) I think it's necessary in this case.)
4.b) I met a guy whom I did not remember to have met before.
Am I right so far?
5.) Past in the future (I don't know what to call this.)
This time tomorrow I hope to have finished my email. (Assuming I won't use too complicated sentences. <self-sarcasm on> )
6.) Imaginary Past
I hoped to have visited you in the States. (But it has never happened.)
7.) I would like (now) to have heard Bing Crosby sing. (He died decades ago. I never heard him sing on stage, and alas, nobody will hear him sing again.) Though I would say in this case: "I wish/If only I had heard him sing." Are there any differences in the meaning between the two sentences?
I must have forgotten about some cases (as usual ), but I think this post is already long enough, and I don't want to squeeze everything into one post. Just one more question... How often is the Perfect Infinitive used among the native English speakers? I only very seldom come across with it, and maybe (only maybe) because the Present Infinitive holds its sway, and for a reason, I think. That's why I put the emphasis on the question of the difference between these two different infinitives, and I admit (as you can see) that I still have doubts. Thank you very much again, Raymott, for helping me understand this stuff.