由若干码元做成一个码组，代表一个字符、数字、指令或字母，这种方法称为（）。
A.扩频
B.编码
C.定时
D.信号
参考答案：B
— Why was she unhappy yesterday?
— A call from home an attack of homesickness. [ ]
A. set off
B. set out
C. set about
D. set down
数值模拟有哪些主要组成部分？
