镶嵌钻石底尖大小对亭深比有一定影响，若底尖（）应在估测的亭深比上减去1%—3%。
A.中等
B.大
C.极大
D.大—极大
参考答案：D
Jack wasn't saying anything, but the teacher smiled at him ________he had done something very clever. [ ]
A. as if
B. in case
C. while
D. though
为什么说赫尔巴特对科学教育学体系的建立作出巨大贡献？
