The tourists will find the guide book is of even ________ practical value than they thought, as it shows different routes to the places they are going to.

A．less

B．little

C．great

D．greater

下列选项中（）未嵌在岳麓书院讲堂的石壁当中。

A.真西山《勿斋箴》碑

B.《六有箴》碑

C.欧阳守道《赠了敬序》碑

D.《王九溪读书法》碑