计算机的主时钟频率常用来表示主机的（）。
A.字长
B.存储容量
C.运算速度
D.性能价格比
参考答案：C
A certain prosthodontist specializes in implanting gold and silver teeth in his patients’ mouths. He charges $650 for a gold tooth and $325 for a silver tooth. If his total fees for implanting gold and silver teeth last week were $15,925 in total, and he implanted five more gold teeth than silver teeth, how many teeth in total did he implant over the week ？（）
A. 31
B. 32
C. 33
D. 34
E. 35
1917年蔡元培执掌北大，由他主导的北大改革具有（）大学的烙印。
A、美国
B、英国
C、日本
D、德国
