此题要求改正所给短文中的错误。对标有题号的每一行做出判断；如无错误在该行右边横线上画一个勾（√）；如有错误（每一行只有一个错误），则按下列情况改正：

　　此行多一个词：把多余的词用斜线（＼）划掉，在该行右边横线上写出该词，并也用斜线（＼）划掉。

　　此行缺一个词：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。

　　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：原行没有错的不要改。

When my father bought me a computer as a birthday gift for me in last year, I felt very excited. As we all know, computers are getting more and more usefully now. Much information can be stored in them. We can also learn that has lately happened in the world on the internet. In the past, people had to do lots of work which was very dangerous. Now, but, computers can do it instead. When an exam is coming, I often did some exercises on my computer. Then it will correct it and tell me the right answers. In this way it is very convenient for me to prepare the exam than before. The computer has become my real friend.

嗜铬细胞瘤切除术中，肿瘤切除后可出现的严重并发症有（）

A.高血压危象

B.严重低血压

C.二氧化碳蓄积

D.心率紊乱

E.高血糖