Problem: Frank was upset with Tom because the toaster *he* had sold him didn't work.

Are "he" and "Frank" the same?
Answer: no

Problem: Steve follows Fred 's example in everything. *He* admires him hugely.

Are "He" and "Steve" the same?
Answer: yes

Problem: John promised Bill to leave, so an hour later *he* left.

Are "he" and "John" the same?
Answer: yes

Problem: I couldn't put the pot on the shelf because *it* was too high.

Are "it" and "the pot" the same?
Answer:
no