关于listviewitem集合

int itemNumber = this.listView1.Items.Count;
string[] subItem0 = {"张颖","销售代表","复信门２４５号"};
this.listView1.Items.Insert(itemNumber, new ListViewItem(subItem0));
this.listView1.Items[itemNumber].ImageIndex = 0;
string[] subItem1 = {"王伟","副总裁","罗马花园８９０号"};
this.listView1.Items.Insert(itemNumber, new ListViewItem(subItem1));
//richTextBox1.Text = Convert.ToString(itemNumber);
this.listView1.Items[itemNumber].ImageIndex = 1;
string[] subItem2 = {"李芳","销售代表","芍药园小区７８号"};
this.listView1.Items.Insert(itemNumber,new ListViewItem(subItem2));
this.listView1.Items[itemNumber].ImageIndex = 2;
当第二次加入的时候它能知道itemNumber的值是1吗?应该变量没有改变啊.那为什么this.listView1.Items.Insert()却能加入到Listview中了。两个加入位置不是一样吗?为什么还能加入啊.