These amazing pens have a great history of being approved for use in space, since they effortlessly write in the gravity free vacuum of space, and at any Angle.

这些令人惊讶的笔有了不起的历史，被批准在太空试用，因为它们在太空失重的情况下或以任何角度都可以轻松自如地使用。

youdao

Photonic band gap (PBG) structures have been shown to have a density of states (DOS) of emission field different from that of free-space vacuum field.

光子带隙结构中的辐射场态密度(DOS)不同于自由真空场中的辐射场态密度。

youdao