'Yesterday' is not an adjective and does not have a comparative degree. It means 'the day immediately before today'. Something cannot happen on 'the day more immediately before today' - it makes no sense.
Expressions such as 'the day before yesterday', 'a week ago yesterday', and so on, are used to indicate dates further in the past, but they do not constitute the comparative degree.
better for its comparative and best for its superlative
The comparative degree form of "pitiful" is "more pitiful."
More truthful and most truthful, respectively.
The comparative degree for "lush" is "lusher."
The comparative degree of "muddy" is "muddier".
The sentence uses the comparative degree of comparison. This is indicated by the word "worse," which compares the level of heat from yesterday to today, suggesting that yesterday's heat was of a greater intensity than today's.
The comparative form of the adjective "sleepy" is "sleepier." This form is used to describe a greater degree of sleepiness in comparison to something else, as in "I feel sleepier today than I did yesterday."
The comparative degree of the word "honest" is "more honest."
better for its comparative and best for its superlative
The answer is comparative.
"Litter" is a noun and a verb and, as such, does not have a comparative degree.
more out
more out
The comparative degree is 'more magnificent' and the superlative degree is 'most magnificent'.
The comparative degree form of "pitiful" is "more pitiful."
nicer
abler