在近代新闻事业的初创阶段,即l7、18世纪,报业中的两个分支开始形成。报业的这两个分支是报纸和( )
A.图书
B.期刊
C.小册子
D.新闻信
参考答案:B
By the time he realizes he________into a trap, it’ll be too late for him to do anything about it.[ ]
A. walks
B. walked
C. has walked
D. had walked
8031单片机扩展外部存储器时,用作数据总线的接口是( )
A.P0
B.P1
C.P2
D.P3