Use it or lose it

In some countries, people brush their teeth more frequently than in other countries

In recent years, the rate of cavities has increased in many countries

In recent years, the consumption of sugar has increased in many countries

The more sugar people eat, the more likely they are to get cavities

weight

distance

brightness

time

telescope

telegraph

telephone

teletype

anti stokes lines

IR

stokes lines

Rayleigh's lines

innermost

all layers at same temp

outermost

middle layer

Airbus

Boeing747

Concorde

Boeing 727