A chalkboard/blackboard
a chalkboard
It gets whiter and thicker when you ovulate.
There is nothing 'whiter than white', because white is already as white as it gets.
A chalkboard becomes whiter as it gets dirtier with chalk dust.
it is usually gray when wet and for the first few years then it gets whiter with age
Comparative: Whiter Superlative: Whitest
Walter Whiter was born in 1758.
Walter Whiter died in 1832.
a snow storm throughout the day, starting around midday
It will not make your teeth whiter.
Washes Whiter Than was created in 1979.
A Whiter Shade of Pale was created in 1994.