Problem: I took the water bottle out of the backpack so that *it* would be handy.

Do "it" and "the backpack" mean the same thing?

Answer: no


Problem: Adam can't leave work here until Bob arrives to replace him. If Bob had left home for work on time, *he* would be here by this time.

Do "he" and "Bob" mean the same thing?

Answer: yes


Problem: Fred is the only man still alive who remembers my great-grandfather . *He* is a remarkable man.

Do "He" and "my great-grandfather" mean the same thing?

Answer:
no