In which language did the young man reply to the writer's greetings.“in”可否省略

21. He showed great interest in the game _____ the young men competed last night. A. which

compete \u662f\u4e0d\u53ca\u7269\u52a8\u8bcd \u540e\u9762\u52a0\u540d\u8bcd\u5fc5\u987b\u8ddf\u4ecb\u8bcd\u3002 compete in \u5728\u67d0\u65b9\u9762\u7ade\u4e89\u3002compete with \u4e0e\u67d0\u4eba\u7ade\u4e89 compete for \u4e3a\u4ec0\u4e48\u800c\u7ade\u4e89\u3002 \u6839\u636e\u53e5\u610f \u5e94\u8be5\u662f \u4ed6\u5bf9\u6628\u665a\u90a3\u4e2a\u5e74\u8f7b\u4eba\u73a9\u7684\u90a3\u4e2a\u6e38\u620f\u5f88\u611f\u89c9\u3002

\u795d\u4f60\u5b66\u4e60\u8fdb\u6b65\u3002

\u90a3\u4e2a\u5916\u56fd\u7537\u4eba\u7528\u81ea\u5df1\u7684\u6bcd\u8bed\u53fd\u53fd\u55b3\u55b3\u7684\u8bb2\u7740\u4e00\u4e9b\u6211\u5b8c\u5168\u542c\u4e0d\u61c2\u7684\u8bdd\u3002

不可以，你试着把这句话转化一下就可以理解了。
The young man reply to the writer's greeting in which language?

in which language表示用那种语言，就像我们说“用英语”---in English。

希望我的回答有助于你的理解。

不可以。
which 引导的是定语从句，which = 前面的“先行词”（定语从句所修饰的名词）。而 in which 表示地点，= “在......”。如果省略了，意思当然不一样了。

不可以。In which language是一个完整的介宾短语，在句中作状语。

不可以，介词不可缺

不可以
in language
不懂问我

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