ComboBox strategies to function

Question

I have four combo box everything does the same as follows

Select Case combobox1.selectedItem

case 0 str=str & "' AND"

case 1 str= str & "'"

end case

select case combobox2.selected item

case 0 str=str & "' AND"

case 1 str= str & "'"

end case

similarly the other two comboboxes have the same body

i want to replace this code block by a method call and implement the select clause body in a method body and call it when required

Please give me a solution