Effects of quality index, which are volcanic ash activity, loss on ignition, fineness and water demand ratio, on quality of fly ash are expatiated, the requests to quality of fly ash are put forward.

阐述了火山灰活性、烧失量、细度和需水量比等品质指标对粉煤灰质量的影响，对粉煤灰品质提出了要求。

Improper combustion, due to a rich mixture, defective ignition system, loss of compression in the engine, a cold engine, and so forth, will result in carbon deposits on the exhaust valves.

因混合气过浓、点火系统有故障、发动机内压力损失、冷机等导致的不正常燃烧都会形成气门积炭。