單項選擇---IsDoctorGreen

問題詳情：

單項選擇

--- 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

知識點：冠詞

題型：選擇題