短文改错。 Yesterday a school boy is daydreaming in class.Not knowing that he was doing,he put a pen cap into his mouth.A few minutes late,he was terrified to find that he had swallowed it!The teacher was shocking when the boy stood up and said,'I've just swallowed a pen cap.'He was quickly sent the nearest hospital.There a doctor examined his and said the best treatment was to take some medicines so that the pen cap could pass natural.Three hours later the boy successfully made it.'She is really lucky,' said the doctor.'It's not rare that small children put things into their mouths for a fun.It's very danger.'