发布于：2025-07-05 22:07浏览量：143文/优校网
1.the reverse flow of gases in a system, e.g. through the carburettor of an internal-combustion engine during the compression cycle
2.the powdery residue that is released or ejected upon firing bullets or shells from a weapon
3.a reaction or effect resulting from an action or cause, usually a negative reaction