1.By the time, you walk out your front door you have already been exposed to thousands of chemicals.
exposed to 容易受到…,易受,易招致,易招惹;露于;朝向
The area where most refugees are waiting is exposed to the elements.
大多数难民等待救济的地方都不能挡风遮雨 。
Audiences' expectations are ratcheted up as they are exposed to high-budget productions.
观众看过高成本影片后期望会相应上升 。
2.On its own, each chemical seems harmless. But in combination with other chemicals, they may become deadly.
on one's own 独立地;独自地;主动地
I live on my own in a studio flat.
我自己住在一个单间公寓里 。
When push comes to shove, you are on your own.
如果形势糟糕,你就只能靠自己了 。