资料题：As a boy, Alfred Adler was poor at arithmetic because（　）。

A person may have an idea about himself that will prevent him from doing god work.He may have the idea that he is not capable of it.A child may think he is stupid because he does not understand how to make the most of his mental faculties, or he may accept another person's mistaken estimate of his ability.Older people may be handicapped by the mistaken belief that they are incapable of learning anything new because of their age.A person who believes that he is incapable will not make a real effort, because he feels that it would be useless.He won't g at a job with the confidence necessary for success.He is therefore likely to fail, and the failure will strengthen his belief in his incompetence.Alfred Adler, a famous doctor, had an experience which illustrates this.When he was a small boy he got off to a poor start in arithmetic.His teacher got the idea that he had no ability in arithmetic, and told his parents what she thought in order that they would not expect too much of him.In this way, theytoo developed the idea,"Isn't it too bad that Alfred can't do arithmetic?" He accepted their mistaken estimate of his ability, felt that it was useless to try, and was very poor at arithmetic, just as they expected.One day Adler succeeded in solving a problem which none of the other students had been able to solve.This gave him confidence.He rejected the idea that he couldn't do arithmetic andwas determined to show them that he could.His new found confidence stimulated him to go atarithmetic problems with a new spirit.He now worked with interest, determination and purpose,and he soon became extraordinary good at arithmetic.This experience made him realize that many people have more ability than they think theyhave, and that lack of success is as often the result of lack of knowledge of how to apply one'sability, lack of confidence, and lack of determination as it.is the result of lack of ability.