Final answer:
The most common adverbs end in -ly and are used to modify verbs.
Step-by-step explanation:
The most common adverbs end in -ly. These adverbs are used to modify verbs, describing their time, place, reason, or manner. For example, in the sentence 'Pierre quickly ran through the main points of his argument', the adverb 'quickly' is modifying the verb 'ran'.