下边一篇短文中有10处错误。请你进行修改，每句中最多有两处，错误涉及一个单词的增加，删除或修改。
增加：在缺词处加一个漏字符号（^），在该行右边横线上写出该加的词。
删除：把多余的词用（/）划掉
此行错一个词：在错的词下划一横线，在该行右边横线上写出改正后的词。
注意：
1．每处错误及其修改均仅限一词。
2．史允许修改10处，多者（从第11处起）不计分。
Walter’s goal in life was become a successfully doctor. He knew he had to finish high
school first, so he put his heart into his study—in particular, biology, chemistry, and maths.
Because he worked hard at these subjects. Walter became good at it. However, Walter forgot
that he needed to master some other subjects beside those he had been chosen. As a result,
Walter fails both English and Latin in the end of the second school year. But he had to repeat
these subjects and he was almost unable to graduate like planned. Walter learned a good lesson.