A．They emphasize the importance of presentations.
B．They provide the author's own presentation experience for us.
C． They tell the difference between good and bad presentations.
D．They teach people how to develop presentation skills.
A．Engaging in interesting debates often.
B．Speaking to ourselves in front of a mirror.
C．Talking with friends about different topics.
D．Writing down ideas and opinions first.
A．Walking around the audience.
B．Smiling while explaining the notions.
C．Telling some jokes during the speech.
D．Sharing some personal privacy.