美国 93%的家庭至少拥有一套感烟报警器。近年来 ,拥有感烟报警器的家庭有所增长 ,住宅失火造成的死亡数几乎降低了一半。但是有些不实用的感烟报警器的数目也在增长。专家警告说 ,如果不尽快处理这些无用的感烟报警器的话 ,那么估计有三分之一的家庭会有这种无法使用的感烟报 93% of households in the United States have at least one smoke alarm. In recent years there has been an increase in families with smoke alarms, and the number of deaths from residential fires has almost halved. However, the number of impractical smoke alarms is also on the rise. Experts warn that an estimated one-third of families will have such unacceptable smoke if they do not deal with these useless smoke alarms as soon as possible