母马的体细胞染色体数为64条,公驴的体细胞染色体数为62条。则母马和公驴的杂交后代骡的体细胞染色体数为 [ ]
A.61条
B.62条
C.63条
D.64条
答案:C
Which of the following describes the regulatory practice of setting prices at a level where the monopoly firm's average total cost curve intersects the demand curve()
A. Average cost pricing.
B. Marginal cost pricing.
C. Cost-of-service pricing.
MCS-51单片机中规定1个机器周期包含______个时钟周期,所以晶体振荡频率为12MHZ时,其机器周期为______μs(微秒)。