单项选择---IsDoctorGreen

问题详情：

单项选择

--- Is Doctor Green ________ ORBIS doctor?

--- No, he is ________ UNICEF volunteer. But he sometimes works with ORBIS.

               A. a; an               B. an; a                 C. an; an                 D. a; a

【回答】

B

知识点：冠词

题型：选择题