fast;fastly

[Silverobama]

Hi,

she speaks so fastly that I can’t catch up with her.​

"Speak" is a very, fastly works as an adverb to modify "verb"​

she speaks so fastly that I can’t catch up with her.​

"So+adj"


Which one is correct?

Thanks

 

[PlacidRan]

She speaks so fast that I can’t catch up with her.
Fastly is obsolete. But if you must use it, then here: She speaks fastly. I can’t catch up with her.

 

[Barb_D]

I don't believe that "fastly" can be used (any longer) as an adverb meaning "quickly." That adverb is "fast."

The only definition I've found for the adverb "fastly" is "firmly." It's not even in the online dictionary for Merriam Webster.

Is it used in other dialects of English?

 

[Silverobama]

I don't believe that "fastly" can be used (any longer) as an adverb meaning "quickly." That adverb is "fast."

The only definition I've found for the adverb "fastly" is "firmly." It's not even in the online dictionary for Merriam Webster.

Is it used in other dialects of English?

Hi, thanks a lot, so do you mean here in the sentence, it must be an adverb to follow "so" as and modifier of "speak"?

 

[Barb_D]

She speaks so quickly that...
She speaks so fast that...

Yes, you need an adverb to modify the verb "speaks."

You could say "Her speech is so fast that..." and then you would use an adjective to modify the noun "speech."