Hi, I find this sentence a bit hard to understand. Especially the “gewesen zu sein” part, what kind of grammar is it? Thanks!
English Translation
He seems to have been ill for a long time.
It’s present perfect tense. It matches the “to have been” part of the English sentence. Note that in English, the perfect tenses always use “to have” as the auxiliary verb:
I have seen that = I saw that
I have done that = I did that
I have been there = I was there
He has been sick = He was sick (and maybe still is)
But in German, the auxiliary verb is “haben” only if we’re not talking about a state of being:
Ich habe das gesehen = I have seen that
Ich habe das getan = I have done that
Er scheint es gesehen zu haben = He seems to have seen it
But when the main verb is describing a state of being, the auxiliary changes to “sein”:
Ich bin dort gewesen = I have been there
Er ist krank gewesen = He has been sick (und vielleicht ist er noch)
He seems to have been sick = Er scheint krank gewesen zu sein