Lesson 23 introduces another combination of preposition and pronoun.
Only part of this combination can be translated to English and therefor it is a bit challenging to explain it.
This combination uses the Hebrew word "Et" as a preposition. Once students get used to include "Et" before a definite direct object, and understand that "Et" cannot precede a pronoun than, it is easy to use it as the other combinations of preposition and pronoun.