Be careful to not touch the dropper or the top of the bottle with anything that could cause contamination: surfaces, objects (especially not your tongue!), or fingers.

注意一定不要用任何东西接触滴管或瓶子上端，这些可能会引起污染的物质包括：物体表面，任何物体(特别是你舌头)，或者你的手指。