The shell is smooth on the inside.

贝壳内壁光滑。

《牛津词典》

This seemed to make sense to the Italians and French who discussed it since the shell of this little ocean dweller was also smooth and white.

对于那些有过相关讨论的意大利人和法国人来说，这似乎是有道理的，因为此类海洋小生物的贝壳看上去同样光滑、白净。

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When they have reached the size they want, they use an implement such as a rock or shell to smooth the surface of the pot.

参考译文：做出想要的尺寸时，他们用一个工具，比如一块石头或贝壳，将罐子的表面弄平滑。

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The top-selling stylish T Series Ultrabook made with an ultra-smooth brushed aluminum shell now comes with a touch display on the new T13 Ultrabook to allow consumers to experience Windows 8-based touch in a clamshell form factor.

ENGADGET: Sony's VAIO Duo 11 Windows 8 slider goes on sale this month, starts at $1,100

The red dirt gave way to smooth, egg-shell-white sand.

FORBES: Life