考试成绩好用英语可以说“to have good grades on exams”。
"Grades"是成绩的意思，"on"是提到考试成绩的介词。这句话的意思就是"在考试中取得好成绩"。
例句：
She always has good grades on exams. (她总是考试成绩好。)
He worked hard to improve his grades on exams. (他努力工作以提高考试成绩。)
I'm proud of my son for having good grades on exams. (我为我儿子在考试中取得好成绩感到骄傲。)