Q: .

I stuck a pin through a carrot. When I pulled the pin out, *it* left a hole.

Do "it" and "the pin" mean the same thing?
A: yes
Q: .

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?
A: no
Q: .

This book introduced Shakespeare to Goethe ; it was a major influence on *his* writing.

Do "his" and "Goethe" mean the same thing?
A:
yes