Question

My son is supposed to correct this incorrect sentence:
He performed the backward somersault more expertlier of all.
According to the rules, part of the sentence should be changed to:
most expertly of all
This sounds strange to me. Did he do it correctly? If not, would you please give me a rule to guide him?

Answer 1

The suffix <i>-er</i> is not used when you use the words <i>more</i> or <i>most</i>. The correct adverb is <i>most</i> because you're comparing more than two performances.

Answer 2

When comparing two items, use the comparative.. er as in taller or more as in more beautiful. John is taller than Henry. My dog is more beautiful than yours is.

When comparing more than two items, use the superlative. est as in tallest or most as in most beautiful.

John is the tallest boy on the team.
My dog is the most beautiful in the dog show.

Check this site.
http://www.uottawa.ca/academic/arts/writcent/hypergrammar/compsupl.html