What does your English teacher speak ? ---Chinese and English .是填language还是languages ,为什么?

应是language
提问者事先不知道你的英语老师会多少语言，所以应用单数
language是不可数名词，languages是可数名词,表示多少种类的语言
language
KK: []
DJ: []
n.
1. 语言;语言文字[U]
Language is an instrument for communication.
语言是交际的工具。
2. (国家、民族等的)语言文字[C]
He can speak several languages.
他会讲好几种语言。
3. (使用文字以外的)表达方式;(动物的)表意方式[C][U]
The deaf and mute communicate by sign language.
聋哑人用手势交际。
4. 语言风格[U]
His prose is written in elegant language.
他的散文写得十分优雅。
5. 强烈的言词,骂人的话[U]
You shouldn't use such strong language.
你不应该使用这样强硬的措词

Language单数

应该是 What languages does your English teacher speak? --Chinese and English.
后面的回答是两个，所以应该用复数。

用复数Chinese and English 的回答是复数。