Can somebody explain how to make a copy constructor for a doubly linked list?

I want to implement the polynomial class using doubly linked list in C++ but i'm having problem with copy constructor

Can somebody explain how to make a copy constructor for a doubly linked list?
That's my mid-test question this morning lol but i can't do it cause i didn't study enough, ask my programming lecturer Mr. Amit Kumar lol. Good luck in finding the answer.

gerbera