10.-Have you been to the Great Wall?-Perhaps not in my memory. _______ , it might have been during my early childhood.
_______ the people have become masters of their country _______ science can really serve the people.
—I would never come to this restaurant again.The food is terrible! —_______.
The old couple have married for 40 years and never once _______ with each other.
I just wonder _______ that makes him so excited.
It was with great joy _______ he received the news _______ his lost son would soon return home.