Source: ABC of common grammatical errors by Nigel D Turton1. I pulled the string tightly. (incorrect)
2. I pulled the string tight. (correct)
If the word that follows an object describes the object, we use an adjective.
3. She painted the kitchen white. (correct)
4. She painted the kitchen quickly. (correct)
I say to myself that the author has made a mistake. Because sentence #1 is acceptable. Because "tightly" describes the act of "pulling". So, #1 should be correct and #2 should be incorrect.
Would you please be kind enough to give me some guidance?