Which of the following is NOT used to control the ventilating current?

The correct answer is based on the function of the items listed concerning ventilating current management in underground mines. Electrical tools are primarily used for operating machinery and conducting tasks such as drilling, cutting, and other operations related to mining, rather than managing airflow in the mine.

In contrast, stopping, auxiliary fans, and check curtains are all components explicitly designed to regulate and control ventilation. Stoppings create barriers to direct and contain airflows within specific areas of the mine. Auxiliary fans enhance the effectiveness of the main ventilation system by helping to circulate and distribute airflow to areas that may not be reached effectively. Check curtains additionally help in guiding airflow by preventing air from escaping certain passages. Thus, while the other options directly influence the movement and management of air in the underground environment, electrical tools focus more on operational functions, which is why they are not utilized to control the ventilating current.