What is the importance of the law of conservation of mass?

of Americans are helped and protected by it? https://www.npr.org/templates/story/story.php?storyId=5323928 ' Mad Luv -- How am I helped by dams built 10 States over? So why shou...

i've heard a lot of bad things about plastic straws (not biodegradable and causing harm to our environment and wildlife), but what about paper straws? are they really the better op...