假如你是某家英文报社的编辑，昨日收到一位中学生读者王丽的来信。请根据来信内容用英语写一封回信。词数120左右。

Dear Editor,

I am a hardworking girl and want to do well in my lessons．But in the exams, I always make mistakes that I should have avoided．I really worry about it．What can I do to improve my performance in exams?

Wang Li

注意：信的开头和结尾已给出，不计人总词数。

Dear Wang Lin，

Editor

自动电压调节器应有两个独立的自动电压调节通道，含各自的电压互感器、测量环节、调节环节、脉冲控制环节、限制环节、电力系统稳定器和工作电源等。两个通道可并列运行或互为热备用。