烟，蒸汽量在一次呼气中散发出的蒸汽、烟雾或类似物质的量 An amount of vapor, smoke, or similar material released in a puff.
自那时起，从埃及的木乃伊头发到石器时代的檀香木等有机物质的年代都已被确定。 Since then, organic materials ranging from Egyptian mummy hair to Stone Age sandals have been dated.
幻影，幽灵明显可见但没有物质的实体；幻影或幽灵 Something apparently seen but having no physical reality; a phantom or an apparition.
物理学家们正在研究对环境危害少的发电新方法，与此同时，许多发电厂也在实现现代化以减少污染物质的释放量。 Physicists are studying new ways of generating electricity with less damage to the environment. In the meantime, many power plants are being modernized to give off less polluting material.
