English is useful language so that most people speak it as second language.A. a; theB. a

English is useful language so that most people speak it as second language.
A. a; the
B. an; the
C. an; a
D. a; a

A. a; theB. an; theC. an; a(答案→)D. a; a解析：英语中以元音音素发音开头的单数可数名词，要用不定冠词an。useful为辅音音素发音，故填a; a second 是又一个，再一个的意思. a second language第二语言.句意：英语是一门很有用的语言，所以很多人将它作为第二语言。

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