Blank Combo Boxes

Hi all, just started learning C# not to long ago and have been able to find most of my answers through google however there is one I'm a bit stumped on.

I have a set of combobox's that contain a list of times. Now I want to be able to leave one of the combobox's blank and use the data from the previous box I'm just unsure of how I would go about doing this.

So you want to add selection(s) made from other comboboxes, to the empty one ¿

You should look into the Items.Add method, and look into the SelectedIndex and SelectedItem properties.