Tallest is the superlative.
bigger is the comparativebiggest is the superlative
smallest is the superlative. (est is the standard superlative ending._
The superlative of clear is clearest.
Fattest is the superlative of fatter.
The superlative of grateful is most grateful.
grateful.* more grateful.* most grateful.
More generous and most generous
Grateful
I'll be forever grateful and I am grateful mean the same thing. Both saying are sad when someone is grateful for something.
Grateful
i am not grateful to you.
There can be many sentences using grateful. One such is, I am grateful to have a friend like you.
grateful as in "I am grateful to you" = kR^itaj~no.asmigratefulness/thankfulness = kArtaj~nyam
Sleep is a noun and does not have a superlative. Sleepy is an adjective and the superlative is "sleepiest."
more grateful
The superlative for willing would be "most willing." There is no one-word superlative.