题型:判断题 Excuse me, where is Johnson? He cannot go home, as his book is lying __________on his desk. [ ]A. openlyB. openingC. opened D. open 查看答案
题型:判断题 下面是关于8259A可编程中断控制器的叙述,其中错误的是A.8259A具有将中断源按优先级排队的功能B.8259A具有辨认中断源的功能C.8259A具有向CPU提供中断向量的功能D.两片8259A级联使用时,可将中断源扩展到16级 查看答案