The son will read a book to his dad should be accepted
I think so to.
Have you used the Report function? That is the right way to suggest alternative translations and it will have a higher chance of being noticed by the course developers.
I agree.. I wrote the same thing and got it wrong :(
I think it's an easier/more literal translation, too.
What is the purpose of -어주- here ? Couldnt we say 읽을 거다?
The 어주다 here means read to or for because 주다 is' to give'
My impression is the intimate "아빠" (intimate: pa/dad) is used only to refer to one's own father or when addressing to him directly.
아버지, (casual, polite: dad/father) otherwise.
아빠 is definitely used in more situations than direct address.
Is 을/ㄹ 거다 future form of the narrative style?
Yes. It's an abbreviation of ㄹ/을 것이다.
Why does Duolingo insist on ‘his’ (and reject ‘The son will read dad a book’)?
The child helps his dad get some sleep, cutie
What is the difference between 거다 and 거야?
Same. 거야 is used in speech language.