Problem: It is not easy to space buttonholes exactly the same distance apart, and it is very difficult to cut them precisely the right size . The tiniest slip of the scissors will make the hole too large, and even one thread uncut will leave *it* too small.

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

Answer: no


Problem: Tom threw his schoolbag down to Ray after *he* reached the bottom of the stairs.

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

Answer: yes


Problem: Frank felt vindicated when his longtime rival Bill revealed that *he* was the winner of the competition.

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

Answer:
no