18.While I was working as a child psychologist,a principal phoned me."I'm baffled,"he said."A child has written an essay called ‘The Properties of the Nucleus.’"His teacher can't understand it.Neither can I."I went to the school and met Mark,an eight-year-old with ginger hair and freckles.He looked like a very ordinary boy to me.I proceeded with the intelligence test."What is Mars"I asked.Most children his age say,"A chocolate bar."He described the planet in detail.He quickly completed the tests,including a math test for much older children.Then he looked at me as if to say:"Can't you come up with something more difficult"I had seen gifted children before,but this boy was "off the map"as far as assessing his IQ was concerned.Mark's principle and arranged for Mark to be tutored by a science teacher.But in many ways he was just a normal child.We wanted him to be socially adjusted as well as intellectually outstanding.So we also encouraged him to join the Club Scouts and we kept him in class with kids of his age for the time being.I asked Mark's parents what they thought of him."He can be a pain in the neck,"his mother said."He asks such impossible questions,"she smiled."But we love him dearly."This was crucial.Like the rest of us,gifted children need to be loved.He gained a first-class honors degree from Cambridge,is now chairman of his own computer company and is happily married with two children. 问题：The author and the principal kept the boy in class with kids of his own age because ( )

A. they didn't intend to pamper the talented boy

B. they thought the boy should learn how to put up with less smart kids

C. they tired to set him up as a model for the class

D. they wanted the boy to be more sociable