I must have been about five when Father gave me some sums to do. I worked at them confidently and showed him the result. He looked at my work and said, "Well, that's not right, and you've got the second one wrong too. But you have got the third one right, and the fourth, and the fifth. Three out of five--not bad.” I started to cry, for I thought that with such a mediocre score I could never become an engineer, which was what Father wanted his sons to be. For some reason. Father would not allow me to forget this incident. He was to tell it again and again to his friends and to me as I grew up. He thought it a charming story and never knew how humiliating “three out of five”was to me. I was branded with that score。