电子数字计算机最主要的工作特点是 ( )
A．高速度
B．高精度
C．存储程序与自动控制
D．记忆力强
参考答案：C
I didn't know _____ yesterday.[ ]
A. why isn't Danny in school
B. why wasn't Danny in school
C. why Danny isn't in school
D. why Danny wasn't in school
