工程师们花了几个月时间改进软件。

The engineers spent months ___refining the software.

Zucchero Fornaciari 十年前在一个全国性节目中被发现，在这段时间里，他磨练并完善了他的音乐。

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

科学家们不断根据新证据改进他们的理论。

Scientists are constantly ___refining their theories based on new evidence.