[It knocks] impersonal use of the verb ‘klopfen’; as in ‘it is raining’

Into! Day, Mrs Venske. (informal way of saying good day)
Good day, Mr Voss. Have you (formal!) my dictionary? (Note the capitalisation of You and the slightly different verb forms: hast du? = do you (thou) have?)
Yes, here is it. I need it no more (again, note the contraction of brauche + es). Thanks.
And who is this young man?
That is a friend of me, G.M.
[C gives A the hand]: Venske, very pleasant! (the ‘sehr = very’ could be dropped)
Learn You also Spanish? (formal You)
That is yes super! (But that’s super)
I have myself yet not decided.
Then decide you yourself now! (Note the slight difference in spelling decide/decided)
Who knows what tomorrow is!
To-a-seeing-again, the gentlemen! (a slightly old fashioned or mocking way of saying goodbye)
[C goes]
Man, is the demanding! (‘die’ is an informal way of saying ‘sie’ = she – is she demanding! Is he demanding! = ist der anstrengend!)