--Mr Green is teacher. He is English teacher.A. a; aB. a; anC. an; aD. an; an

问题补充：

----- Mr Green is teacher. He is English teacher.

A. a; a

B. a; an

C. an; a

D. an; an

答案：

A. a; a

(答案→)B. a; an

C. an; a

D. an; an

解析：英语不定冠词的用法主要是看后接单词的词首音素是否为元音，元音前用an，辅音前用a。Teacher词首音素为辅音，English词首音素为辅音，故选B。