—Have you been to the Great Wall?—Perhaps not in my memory.________,it might have been during my early childhood.
________ a vocation, and you’ll forget unhappy things
---Why do you look so upset? ---There are so many troublesome problems _____.
The cancer risks ___________ smoking have been well documented.
They are purely __________ weapons, not designed for attacks.
It's not by any means a brilliant salary but it's ________for our needs.