设教务分析百分制学生成绩时认为90分以上为优，80~89分为良，70~79分为中，60~69分为及格，60分以下为不及格。输入某学生百分制成绩，将其转换为上述等级评分后输出。要求用if语句和switch语句两种方法编程。并注意输入数据的正确性和合法性验证。-Let the Senate analyze student achievement percentile more than 90 points when considered as excellent, 80 to 89 were divided into good, divided in 70 to 79, 60 to 69 are classified as pass, 60 points or less failed. Enter a student percentile scores, to convert it to the scoring output. Asked to use if statements and switch statements are two ways to programming. Note that the input data and the correctness and legality verification.