Its hard to know for certain, but they are practice questions only and we think their intention was illustrative and not meant to focus you on technology generations of anesthesiologists have not seen outside a glass case. We are focused on the traditional concepts the ABA has been testing on more recently, not diluting our material with hundreds of questions that are unlikely to be asked... such as copper kettles and drop ether. Besides there are other great resources you can use for this. https://archive.org/details/Opendropether1-wellcome