经常在十六进制数的后面添加（）字母表示。
A.H
B.B
C.D
D.O
参考答案：D
Our school is having a sports meeting. Someone _____ here already. [ ]
A. arrived
B. have arrived
C. has arrived
Web服务器是一个程序，通过它将网页转给Internet浏览器。
