The Jewish leaders know that Nicodemus is not from Galilee. They ask this question as a way of scoffing at him. Alternate translation: "You must also be one of those inferior persons from Galilee!" (See: [[rc://en/ta/man/translate/figs-rquestion]] and [[rc://en/ta/man/translate/figs-explicit]])
This is an ellipsis. You may wish to include the information that does not appear. Alternate translation: "Search carefully and read what is written in the Scriptures" (See: [[rc://en/ta/man/translate/figs-explicit]])