What is a 3ly sentence?

There's no such thing as a "3ly sentence" in the way you might be thinking.

Here's why:

* "Ly" is a suffix, not a sentence structure. It's added to adjectives to form adverbs (e.g., "quick" becomes "quickly").

* Sentences need a subject and a verb. They express a complete thought. A single word, even one ending in "-ly", can't form a sentence.

Perhaps you're thinking of something else? Could you clarify what you mean by "3ly sentence"?

If you have a different question about grammar or language, feel free to ask!