某大臣向汉武帝建议说：“愿陛下令诸侯得推恩分子弟，以地侯之。彼人人喜得所愿，上以德施，实分其国，不削而稍弱矣。”汉武帝采纳他的建议后  [ ]

A．颁布实施“推恩令”          

B．保留郡国并行制度

C．“崇儒尚法”                 

D．废除分封制

--- 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