問題詳情:
單項填空 在A、B、C、D四個選項中, 選出可以填入空白處的最佳選項。
Mr Liu is ____ unusual teacher. He has written _____ useful book for his students.
A. an; an B. an; a C. a; a D. a; an
【回答】
B
知識點:冠詞
題型:選擇題