This section is from the book "Lessons In English", by Chestine Gowdy, Lora M. Dexheimer. Also available from Amazon: Lessons in English.
Some adverbs admit of comparison. They are compared in the same way that adjectives are. But they are generally longer than adjectives, and consequently fewer of them are compared by the use of er and est. Adverbs ending in ly are generally compared by the use of more and most.
 
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