An adjective describes a noun.
Pale is the word that you would use as an adjective.
vacillating
It is an adjective. To use it as an adverb, you would add -LY (vacantly).
To use squeak as an adjective, you would say squeaky.He was a squeaky little mouse.
Stubborn
When writing a sentence
"Ocean water has more salt than fresh water."
you use marine to describe a fish
As strong as an ox.
You would have to use the adjective form, which is expeditious. "An expeditious program of renovation allowed the factory to continue its operations."
Pure is "Puro/a" and Clean is "Limpio/a" If the object that your are describing is masculine, then you would use the 'o' ending on the adjective. If the object is feminine, then you would use the 'a' ending on the adjective.