________ has a lowrelative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable.

A. worst, ventilation B. poor ventilation C. better ventilation D. none of the above

A. Tractive B. Portative C. Either of the above D. None of the above

A. Method of average losses B. Equivalent current method C. Equivalent torque method D. Equivalent power method E. All of the above

A. solid B. hollow C. perforated D. any ofthe above