大家好，请帮帮小弟的忙啊~~~~~~~~~~~~~
代码如下：
    public partial class Form1 : Form
    {

        private DataSet dataSet = new DataSet();
        private SqlDataAdapter dataAdapter;
        SqlCommand comm;
        SqlDataReader dataReader;

        string PaperId;
        string PaperName;
        string GradeName;
        string SubjectName;
        string Count;
        string GenerateTime;

        string ii = "";

        public Form1()
        {
            InitializeComponent();
        }

        private void SelectAll()
        {
            string sqlSelect = "select PaperId,PaperName,GradeName,SubjectName,Count,GenerateTime from TestPaper";
            dataAdapter = new SqlDataAdapter(sqlSelect, DBHelper.conn);
            dataAdapter.Fill(dataSet, "TestPaper");
            dataGridView1.DataSource = dataSet.Tables["TestPaper"];
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            SelectAll();

            //设置自增长字段不显示并别改变字段头名字
            dataGridView1.Columns[0].Visible = false;
            dataGridView1.Columns[1].HeaderText = "试卷名称";
            dataGridView1.Columns[2].HeaderText = "适考年级";
            dataGridView1.Columns[3].HeaderText = "科目名称";
            dataGridView1.Columns[4].HeaderText = "试题数量";
            dataGridView1.Columns[5].HeaderText = "生成时间";
        }

        private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {
             PaperId = Convert.ToString(dataGridView1.SelectedRows[0].Cells["PaperId"].Value);
             PaperName = Convert.ToString(dataGridView1.SelectedRows[0].Cells["PaperName"].Value);
             GradeName = Convert.ToString(dataGridView1.SelectedRows[0].Cells["GradeName"].Value);
             SubjectName = Convert.ToString(dataGridView1.SelectedRows[0].Cells["SubjectName"].Value);
             Count = Convert.ToString(dataGridView1.SelectedRows[0].Cells["Count"].Value);
             GenerateTime = Convert.ToString(dataGridView1.SelectedRows[0].Cells["GenerateTime"].Value);
             button1.Enabled = true;
             //MessageBox.Show(string.Format("{0},{1},{2},{3},{4},{5}", PaperId, PaperName, GradeName, SubjectName, Count, GenerateTime));
        }

        private void button1_Click(object sender, EventArgs e)
        {

            string[] row = new string[] {PaperId,PaperName,GradeName,SubjectName,Count,GenerateTime};
            object[] rows = new object[] { row };

            // 指定DataGridView控件显示的列数
            dataGridView2.ColumnCount = row.Length;
            dataGridView2.ColumnHeadersVisible = true;

            //设置DataGridView控件的标题列名
            dataGridView2.Columns[0].Name = "试题编号";
            dataGridView2.Columns[0].Visible = false;
            dataGridView2.Columns[1].Name = "试卷名称";
            dataGridView2.Columns[2].Name = "适考年级";
            dataGridView2.Columns[3].Name = "科目名称";
            dataGridView2.Columns[4].Name = "试题数量";
            dataGridView2.Columns[5].Name = "生成时间";

            for (int i = 0; i < 6; i++)
            {
                ii = this.dataGridView1.Rows[i].Cells[0].Value.ToString();  //未将对象引用设置到对象的实例。(报错！)
                MessageBox.Show(ii);
                if (ii != PaperId)
                {
                    foreach (string[] rowArray in rows)
                    {
                        dataGridView2.Rows.Add(rowArray);
                    }
                }
                else
                {
                    MessageBox.Show("您选中添加的试题已经存在！");
                }
            }
        }
    }

应该没事啊  我来试试！

估计是下标越界了，调试吧，一看就明白了