Zhao Yan: Look at this photo, Wang Ying.

Wang Ying: Oh, I remember. It was Liu Ning, you and I that were at the gym. It was rainy that day. We went to the gym to watch Lin Dan play badminton. He played with a player of Australia. We yelled for Lin Dan. He played very hard. Finally he won. We were happy. We jumped up and down.

⑴Zhao Yan, Liu Ning and Wang Ying ____      A. happy.

⑵They watched ____                          B. won.

⑶Lin Dan played with ____                    C. were at the gym.

⑷Lin Dan ____                                D. a player of Australia.

⑸We were ____                               E. a badminton game.

下表是一场学术研讨会的活动安排。据此推测，此次研讨会的主题应该是（    ）