Last thursday, I expressed my graduation presentation. I expressed sex and Americans. May be everybody gets nervous when they are in front of an examiner. I was very tension but, my subject may be a matter of common interest. So, monotonous mood changed about mood enjoy. So I was lacking seriousneses when many people started laughing. So, I expressed a half without tension. But if I again exprees presentation, I cannot it. May be I have a heart attack.