该职位的关键要求之一是熟练掌握日语的口语和书面语。

One of the key requirements for the position is ___fluency in both spoken and written Japanese.

为了提高我的德语流利度，我计划在柏林学习一个夏天。

To enhance my ___fluency in German, I plan to spend a summer studying in Berlin.

他在多种语言上的流利程度使他成为国际团队的理想人选。

His ___fluency in multiple languages made him an ideal candidate for the international team.