Some list box in the browser will allow you to select multiple items. Usually, any list box that shows multiple items at one time allows multiple selections.
To select more than one item at a time, hold down the <crtl> key and right click on the first item. Then, with the <ctrl> key still pressed, continue right clicking on the additional items you want. Each item is highlighted as you click it. If you <crtl>+click an item that is already highlighted, it becomes unselected (and unhighlighed). If the list box contains many items, you may have to scroll the list box to find the item you want. See
If you want a continuous range of items (like the 2nd, 3rd, 4th, and 5th items), you can click and drag the mouse to select the range.
You can also combine the click+drag and the <crtl>+click. So, for example, to select the 2nd, 3rd, 4th, and 7th items, click and drag from the 2nd to the 4th items to highlight them. Then <ctrl>+click the 7th item.
You can practice on the list box below