All adverbs ending in -ly and certain other adverbs,especially long ones, form the superlative by the addition of the word most orleast. Some short or irregular adverbs, however, form the superlative by the additionof the ending -est.
The disinfection system works best with a 3% hydrogen peroxidesolution.[well changed to superlative form best with ending-est]
The program is designed to work most efficiently in a 32-bitenvironment. [superlative with most]
Most surprisingly, the experimental data matched our predictionsperfectly. [superlative with most]
If you are not sure how to form the comparative or superlative degreeof a particular adverb, check the adverb in a dictionary.
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