What are the precautions when using fire extinguishers?

Extinguish Class A fires can choose water-type fire extinguishers, foam fire extinguishers, ammonium phosphate dry powder fire extinguishers, halogenated alkane fire extinguishers; extinguish Class B fires can choose foam fire extinguishers (chemical foam fire extinguishers are limited to extinguishing non-polar solvents), halogenated alkane fire extinguishers, dry powder fire extinguishers, carbon dioxide fire extinguishers; extinguish Class C fires can choose dry powder fire extinguishers, halogenated alkane fire extinguishers, carbon dioxide fire extinguishers, etc.; extinguish Class D Fire can choose special dry powder fire extinguishers, powder graphite fire extinguishers, can also be used instead of dry sand or cast-iron chip foam. Fighting electrically charged fires can choose halogenated fire extinguishers, dry powder fire extinguishers, carbon dioxide fire extinguishers, etc.; electrically charged fires refer to household appliances, electronic components, electrical equipment (computers, copiers, printers, fax machines, motors, generators, transformers, etc.) and wire and cable burning when still electrically charged fires, while the top hanging, wall-mounted daily lighting fixtures, and fires can be cut off by the power supply of their own equipment occurred The fire should not be included in the scope of live fires.