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

在硬质面包烘烤过程中，不宜频繁地开关烤箱炉门，造成炉内湿度过早过快降低，使成品较干硬，影响成品质量。