School stories：
(1)H2O：One day the science teacher asked the class,“What's the chemical formula for water?“A boy put up his hand, and the teacher said,”“Yes?”the boy said“HIJKLMNO”．“Are you trying to be funny?”asked the teacher angrily．“No, sir．”said the boy．“You said the formula was H to O．”
(2)10＋20：A teacher was trying to teach a little girl to add．So she asked the girl,“If I have ten apples in my left hand, and someone puts twenty apples in my right hand, what have I got?”The little girl thought and then said,“Big hands．”
(3)I am…：A teacher was testing her pupils on English grammar．“Who can make a sentence beginning with I?”she asked the class．Lots of girls put their hands up, and the teacher chose one of them．The girl began,“I is…”,“No．”the teacher said．“You must say I am．”“OK．I am the ninth letter of the alphabet(字母表)．”
Choose the best answer from A, B or C according to what you read．
