Topics: Ask an American – Saving the oldest photograph; law versus rule versus policy; to stem from versus to be derived from; bring it on; infomercial; hawking; exercise fad

Words:

studio

to show (something) off

luminous

three-dimensional

nanoparticle

to scatter

nanotechnology

unwittingly

degradation

to corrode

chemical mechanism

to preserve

law

rule

policy

to stem from

to be derived from

bring it on

infomercial

to hawk

exercise fad