Look at book on the desk . Is it useful one ?---Yes it is . In the book there is mu

问题补充：

--- Look at book on the desk . Is it useful one ?

---Yes, it is . In the book there is much advice on how to learn math well.

A. a, the

B. the, a

C. the, an

D. a, an

答案：

A. a, the

(答案→)B. the, a

C. the, an

D. a, an

解析：考察冠词用法.定冠词the用于名词前表示特指某一个,不定冠词用于名词前表示泛指任何一个.根据题意,前文特指桌子上面的书,用the,下文泛指任何一个,故用不定冠词,.不定冠词根据后面单词发音的词首音素决定用a还是用an.useful首字母虽然为元音字母,但是读音词首音素为元音,故用a,选B.