在HART通信时主要以（）信号作为载波信号，其中“1”表示采用（）Hz，“0”表示采用（）Hz。
参考答案：数字音频、1200、2200
确定针刺方向的因素有（）。
A、患者体位
B、病灶的位置
C、经脉循行的方向
D、患者形气
E、腧穴的特点
For many years, the principle goal of computer (73) was to write short pieces of code that would execute quickly. The (74) needed to be small, because memory was expensive, and it needed to be fast ,because processing power was also expensive.
A．users
B．programmers
C．computer
D．program
