Multiline selection in a list box

There is 5 items in a List box
When i click Item1 , textbox1 becomes visible.
When i click Item2,textbox2 becomes visible.
and so on.

This i am able to do

Code:

private void lsb_SelectedIndexChanged(object sender, EventArgs e)
        {
            String tempValue;
            foreach (Object obj in lsb.SelectedItems)
            {
                tempValue = (String)obj;           
                    if (tempValue.ToLower() == "Item1")
                    {
                      textbox1.Visble=true;
                      //Rest texbox are invisible by individually setting textbox2,textbox3,textbox4 visiblity property to false.
                    }
                   else if (tempValue.ToLower() == "Item2")
                    {
                      textbox2.Visble=true;
                      //Rest texbox are invisible by individually setting textbox1,textbox3,textbox4 visiblity property to false.
                    }
             }
}

My Question is that,how can i do this
When I select Item1 and Item2 both,both textbox1,textbox2 should be visible
or when i click the three Items,corrosponding 3 textboxes should be visible
I have problem in the code,as When i click Item1 and Item2,tempValue contains Item1 only..
so it goes to the first loop.
How can i achieve this multiline selection of items?