The top visible surface of the keys should be unpolished.

键顶的可视表面应该是无光泽的。

Even in this unpolished form the content of the letter is clear.

尽管翻译的很糟糕，但是信中的内容是清楚地。

An unpolished instrument is not usable. That's the same with men.

尚未被造就的东西就无法好好地供人使用，人也是一样。

Afternoon lowers on evening; the sky is the color of unpolished silver.

下午渐去，薄暮来临；天空是暗银色。

Afternoon lowers on evening; the sky is the color of 5 unpolished silver.

下午渐去，薄暮来临；天空是暗银色。