Question

－What do you think of the grammar book?

－Oh, it really is _________ useful reference book, which is worth reading _________ second time．

[　　]

A．

a; a

B．

an; the

C．

an; a

D．

the; the

Answer 1

答案：A
解析：

a useful reference book表示“一本有用的参考书”，useful的第一个发音是［ju：］，属辅音开头，故用a; a second time表示“又一次”，作状语，故用不定冠词a。