Shallower, shallowest. More shallow, most shallow. Both forms are acceptable, but the first (..er, ..est) is probably more commonly used.
The comparative form is "shorter" (not as high or tall). The superlative is "shortest."
Smaller
Smaller. The superlative form is smallest.
Shorter is an adjective. It's the comparative form of short.
Below is an adverb. The comparative form is more below.
Quicker is the comparative form of quick.
shallower
shallower
The comparative form of solid is solider
The comparative form of in is inner.
comparative - merrier superlative - merriest
"Shine" is a verb and a noun and, as such, does not have a comparative form. The comparative form of the adjective shiny is shinier.
shallower
Comparative: shallower Superlative: shallowest
shallower, shallowest
The comparative form of dreamy is dreamier
The comparative form of many is more
The comparative form of "softly" is "more softly."
The comparative form of solid is solider
The comparative form of handsome is handsomer
The comparative form of good is better.
"Truer" is the comparative form of true.
The comparative form of full is fuller
The comparative form of sunny is sunnier.