Linq 实现两个对象实例List之间的赋值

public class UserCopy
{
    public class LoginEntity
    {
        public string UserName { get; set; }
        public string UserPwd { get; set; }
        public DateTime ActiveTime { get; set; }
    }

    public class UserEntity : LoginEntity
    {
        public string UserID { get; set; }
        public Int16 UserSex { get; set; }
        public Int32 UserAge { get; set; }
    }

    protected void UserCopy()
    {
        List<UserEntity> userList = new List<UserEntity>() { 
            new UserEntity(){
            UserID="U1",
            UserName="U1",
            UserPwd="U1PWD",
            ActiveTime=DateTime.Now
            },
            new UserEntity(){
            UserID="U2",
            UserName="U2",
            UserPwd="U2PWD",
            ActiveTime=DateTime.Now},
            new UserEntity(){
            UserID="U2",
            UserName="U2",
            UserPwd="U2PWD",
            ActiveTime=DateTime.Now}
            };

        List<LoginEntity> loginList = new List<LoginEntity>();
        //关键代码：遍历赋值
        userList.ForEach(user => loginList.Add(new LoginEntity()
        {
            UserName = user.UserName,
            UserPwd = user.UserPwd,
            ActiveTime = user.ActiveTime
        }));
    }
}