Question

(tco 2) what is the c# code that refers to the third item in a check box list control named cblparts?

Answer 1

The CheckBoxList control is in the  System.Web.UI.WebControls namespace (so not winforms!). It has an Items[] indexer to get to the items. Counting starts at 0, so the third item would be:

cblparts.Items[2]

Answer 2

Definition. TCO2 rate. (Abbreviation) Test of Carbon Dioxide (CO2) aka Bicarbonate Test. A test devised to measure the amount of carbon dioxide in blood