Console.Title = "練習：在控制台中錄入一個成績，根據成績計算等級";
Console.WriteLine("請輸入成績：");
//int score =int.Parse(Console.ReadLine());
float score =float.Parse(Console.ReadLine());
string message; //成績，信息
if (score < 0 || score > 100)
message = "成績有誤";
else if (score >= 90)
message = "優秀";
else if (score >= 80)
message = "良好";
else if (score >= 60)
message = "及格";
else
message = "不及格";
Console.WriteLine(message);