Part per billion是什么意思？

• silver
• tourist
• droplets
• crayon
• 解决方案英文
• disappointed
• passage
• toxicity
• bothering
• 纪念品英语
• passage
• approaches
• aspect
• peeping
• 造型的英文
• conflict
• permitted
• 抛弃英文
• 呼吁英语
• brat
• pear
• ultra
• sweater
• narrow
• rice
• panicked
• 领域英语
• erased
• failure
• tomato

• emergency
• scared
• bombarded
• 流浪者英文
• lake
• modernize
• committing
• 队长的英文
• various
• saturday
• general
• firmness
• client
• text
• 实施英文
• searches
• neck
• 参与者英文
• amazing
• fake
• mind
• searches
• 导师英文
• 长颈鹿英语怎么说
• banger
• 局外人英文
• 权限英文
• vehicle
• PEGGING
• general

• work area
• good taste
• ninetieths
• nameless death
• poll parrot
• good humour
• soft tissue
• psychopathy
• auxiliary booster
• equi
• learn to read
• artificial flower
• portioning device
• axial cell
• A drink
• European fish
• wave beam
• swordman
• urinates
• Before dinner
• one aspect