题干
—This is a useful dictionary, I think.
—So it is, and it's __________ unusual one.
A：the
B：an
C：a
D：不填
答案(点此获取答案解析）
B
—This is a useful dictionary, I think.
—So it is, and it's __________ unusual one.
A：the
B：an
C：a
D：不填
