productive ·adjective (USEFUL)

我们开了一个非常有成效的会议，解决了很多问题。

We had a very ___productive meeting and sorted out a lot of problems.

当然，你可以学到东西，但当它们自由时观察它们会更有效果。

Of course, you can learn things, but it would be more ___productive to observe them when they are free.

她的研究在推动医学科学方面非常富有成效。

Her research has been highly ___productive in advancing medical science.