工程师们花了几个月时间优化软件。

The engineers spent months ___refining the software.

Zucchero Fornaciari 十年前在一场全国性演出中被发现，在这段时间里，他磨砺并完善了自己的音乐。

Zucchero Fornaciari was discovered ten years ago in a national show and during this period of time has sharpened and ___refined his music.

科学家们根据新证据不断精炼他们的理论。

Scientists continuously ___refine their theories based on new evidence.