When the expression first came into being, people refused to use it but _____ they began to accept it.

　 A. usually　 　　　　 B. gradually　 　　　 C. frequently　 　　　 D. quickly

 When the expression first came into being, people refused to use it but _____ they began to accept it.

   A. usually                       B. gradually                  C. frequently                 D. unwillingly

 When the expression first came into being, people refused to use it but _____ they began to accept it.

   A. usually                       B. gradually                  C. frequently                 D. unwillingly