单选题 Father: How's your day at school, Costa?Costa: 56, Daddy! It's a day I will never forget.Father:Oh,is it? 57,my son?Costa:I have been made the chairman of the Students' Association.Father :That's great.请作答此空 !Costa: 59Father :That's really nice. You stood first in the examination and now you have won the chairman-ship.60,my son.Costa : Thank you, Daddy.