In the experiment class, which of the following measures shall be taken to protect against electric shock: ()
A、Do not place drinks, cups and other items on the experiment table.
B、Do not touch experiment devices, instruments and equipment with wet hands.
C、Connect the circuit on an insulation pad carefully according to the circuit diagram, and check it after it is connected. If necessary, ask the teacher to recheck it to ensure that it is correct before switching on the power supply. If it is necessary to change or disconnect the line during the experiment, cut off the power supply before performing any operation.
D、If any abnormal phenomena arise during the experiment such as heating, luminescence, sound and smell, cut off the power supply immediately, report to the teacher and identify the cause to prevent failure propagation.