mscorlib.dll中出现未处理的“System.ArgumentOutOfRangeException”类型异常，

Question

其他信息：索引超出范围。必须是非负数且小于集合的大小

这是代码 - ＆gt;

courseList.Add(new Course("Programming", "A190", new DateTime(2012, 09, 1), 
               new DateTime(2014, 06, 28), "The Programming course involves the units – Software Development using VC#, Databases, Information Theory and the Project Unit.", 
               "Abbey Park", 
               2, 
               unitList[0], 
               unitList[2], 
               unitList[3], 
               unitList[6]));