The answer key is missing a word…
The sentence is
Cernisne omnia quae tibi scienda sunt?
My translation is
How do you distinguish all who must be known by you?
Benissimus’s is
"Do you all the things which should be known by you?
Thanks for your help!
Thanks for the correction
The sentence is
Cernisne omnia quae tibi scienda sunt?
My translation is
How do you distinguish all who must be known by you?
Problems:
No word meaning “how”
“omnia” cannot refer to people (it’s neuter) and so by extension quae must be neuter as well (i.e.not “who”)