That is an air (electric) powered grinder (portable grinder, angle grinder, straight grinder, drill, impact wrench, riveting hammer, hammer drill).

• 那是一个气（电）动砂轮机（手持砂轮机、角型砂轮、直型砂轮、钻机、冲击扳手、铆钉锤、锤钻机）。