帮我看一下，怎么改，最好说明一下原因！！谢谢！

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace _55555555555
{
    class Class1:object
    {
        private string firstName;
        private string lastName;
            private string socialSecurityNumber;
                private string grossSales;
                    private string commissionRate;
        public CommissionEmployee(string first,string last,string ssn,decimal sales,decimal rate)
        {
            firstName =first ;
            lastName =last ;
            socialSecurityNumber =ssn ;
            GrossSales =sales ;
            CommissionRate = rate ;
        }
        public string FirstName
        {
        get
        {
        return firstName;
    }}
      public string LastName
        {
        get
        {
        return lastName;
    }}
      public string SocialSecurityNumber
        {
        get
        {
        return socialSecurityNumber;
    }}
      public decimal  GrossSales;
    {
        get
        {
        return grossSales
        }
    set
{
    if(value >=0)
    grossSales=value;
    else
    throw new ArgumentOurOfRangeException("GroaaSales",value,"grossSales must be>=0");
}
}
      public decimal CommissionRate
        {
        get
        {
        return comssionRate;
    }
set
{
if (value>0 && value<1)
commissionRate =value;
else
throw new ArgumentOutOfRangeException("CommissionRate",value,"CommissionRate must be>0and<1");

}

    }
public decimal Earnings()
{
return commissionrate*grossSate;
}
public override string ToString()
{
return string.Format(
"{0}:{1} {2} \n{3}:{4}\n{5}:{6:C}\n{7}:{8:F2}",
"commission employee",firstName,LastName,
"social security number",SocialSecurityNumber,
"gross sales",GrossSales,"commission rate",CommissionRate
);

    }
}
class object --------------------编程问答-------------------- 抄东西都抄不明白，乱七八糟的。类名和构造函数都对不上。
这种问题懒得理，因为没必要理，不可能学明白的。 --------------------编程问答-------------------- 类名和构造函数都对不上，除了这个，还有吗？ --------------------编程问答-------------------- class Class1:object  改成  class Class1:CommissionEmployee 看看

补充：.NET技术 ,  C#