1. At last, he and his friends finished the work _____ (success).
2. That is a _____ (use) book.
3. I saw Dick _____ (do) his homework just now.
4. It is dark now. We have to _____ (stop) the work.
5. Mr. Brown is learning English for _____ (busy).
6. It is important _____ (plant) more trees.
7. Please teach us how _____ (bake) cookies.