短语词组短语Fall -out ratio 误检率downwind fall -out 顺风落尘tropospheric fall -out 对流层沉降upwind fall -out 上风落尘global fall -out 全球性散落local fall -out 区域落尘cloth fall -out 坯布脱套fall -out sediment 可沉降物radioactive fallout 放射性尘降物 返回 fall-out