I must be nervous. I remember I was nervous when I answered questions. The teachers kept a straight face. As a result, a teacher asked the simplest question, how many kilometers is a nautical mile? I answered 1.87, and the teachers immediately looked at me in surprise. I added painfully, "I am so nervous that I have tightened 5 and 2 together nervously." The teachers couldn't help laughing, so I saved myself. The atmosphere suddenly became harmonious and I passed the defense smoothly.