藉新技术即能从废弃物中回收<em>可用</em>之物。
New techniques make it possible to recover usable things from waste.
安全曝光的时限价值或情况的范围，尤指曝光范围，在此期限内摄影用的底片能产生<em>可用</em>的影象
A range of values or conditions, especially the range of exposures over which a photographic film yields usable images.
