spoken是动词speak的过去分词形式，在句中作定语，修饰主语language, spoken 与 language有被动关系。该句可以理解为

What’s the language (which is) spoken in German?

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关于汉语被动句的第二语言习得研究，现有的研究主要是关于被动句的语法形式的习得，关于被动句语用功能的习得还不多见。

The achievements of acquiring Chinese passive sentence in second language acquisition are mainly in the acquisition of grammatical pattern, and seldom in the acquisition of pragmatics function.

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英汉语在被动句原型和特殊形式方面，既相似又相异，我们把这种现象看成是认知语义结构基底的表层变体。

The differences between the prototypical and non prototypical forms in both languages are surface variants of corresponding deep structures. Some motivations for such variants are also discussed.

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