(Best is an adverb describing how, or to what degree, she wrote.) In the world of grammar, the misuse of adjectives and adverbs is a minor yet quite common thing.

Adverbs of degree can answer questions such as ‘to what extent’ or ‘to what degree’. They also function as modifiers of adjectives and adverbs. Look at this sentence: ...

Quantifiers and intensifiers are adverbs used to talk about quantities, amounts or degree, such as enough, a lot or a little. Learn about quantifiers and intensifiers with BBC Bitesize Spanish.

That Casimir Markievicz exhibition (Diary, April 23rd) reminded me in passing how dependent the upper classes of these islands used to be on what grammarians call “degree adverbs”.