The girl often ______________ her grandparents. [ ]
A. visit
B. visits
C. visiting
答案:B
设8255A的四个端口地址分别为00C0H、00C2H、00C4H和00C6H,要求用置0、置1的方法对PC6置1,对PC4置0。
副轮、幼轮的形成原因及其鉴别特征。