Question

【题目】—This is ____________ useful book, I think.
—So it is, and it's ____________ unusual one.
A.an; /
B.an; an
C.a; an
D.a; a

Answer 1

【答案】C
【解析】不定冠词表示数量一，useful是辅音音素开头，用a; 而unusual则是元音音素开头，故用an。句意：—这是一本很有用的书，我认为。—的确是，而且它是一本不寻常的书。故选C。