a productive effort的用法和样例：
- If the answer is a methodical working through of some of the difficult issues raised by a large and growing trade relationship, this could still prove to be a productive effort.
- A result of creative effort; a product.
- A product of a document copying process.
- She was elected a puodrctive worker.
- Flower power was a product of the sixties.
- It cost a lot of money to develop a product.