I listened to Dr.Wilson’s lecture about the protection of wild animals,but I was unable to grasp its key _________.

The top leaders of the two countries are holding talks in a friendly________.

Zhang Yimou, a two-time winner in the Venice International Film Festival, has all the right __________to become the Best Director of China. 

Mary was praised by the headmaster in public and on that _______ she was simply proud.

As far as I know, this is a type of music popular in the 1950s, a(n) _____ of jazz and folk music.