But on the other hand, the use of over-fireair reduces the combustion efficiency of pulverized coal.
但另一方面，燃尽风的应用将导致煤粉燃烧效率下降。
2
Keep the warm air inside your home by placing a piece of approximately 2 foot-by-3 foot plywood over the mouth of your fireplace to prevent drafts going up the chimney when you're not having a fire.
保持室内的暖空气，可以通过在你家壁炉入口处放一块大概2到三英寸的夹板来防止你不用火时风进入烟囱。
3
During the Second World War, when a young group of pilots in the RAF were fighting for their lives in the airover England, they would often be hit by enemy fire.