Complete the amazed pet owner's text message with the right word.

I didn't know turtles could move ___ quickly, but Barnaby just sprinted across the living room!

The correct answer is so.

We use so directly before an adverb (like "quickly") or an adjective to make it stronger.

• We use such when there is a noun following the adjective/adverb (e.g., "He is such a fast turtle"). Since "quickly" is an adverb describing how the turtle moves, and there is no noun after it, "so" is the perfect fit!