Problem: The table won't fit through the doorway because *it* is too narrow.

Are "it" and "the doorway" the same?
Answer: yes

Problem: The foxes are getting in at night and attacking the chickens . *They* have gotten very nervous.

Are "They" and "The foxes" the same?
Answer: no

Problem: The pony behaved well, sir, and showed no vice; but at last he just threw up his heels and tipped the young gentleman into the thorn hedge. *He* wanted me to help him out, but I hope you will excuse me, sir, I did not feel inclined to do so.

Are "He" and "young gentleman" the same?
Answer: yes

Problem: The mothers of Arthur and Celeste have come to the town to fetch them. They are very happy to have them back, but *they* scold them just the same because they ran away.

Are "they" and "Arthur and Celeste" the same?
Answer:
no