单选题 ______ a language family is a group of languages with a common origin and similar vocabulary, grammar, and sound system.
A. What linguists call B. It is called by linguists
C. Linguists call it D. What do linguists call

【正确答案】 A

【答案解析】[解析] 语法应用。
本句是用名词性从句What do linguists call a language family作主语；意思是语言学家将一组有着共同起源，类似词汇、语法及音系的语言称为语系。