The program memory serves basically as a place (1) instructions, the coded pieces of data (2) direct the activities of the control processing unit (CPU). A group of (3) related in- structions stored in memory is referred to as a program. The CPU "read" each instruction from memory a logically (4) sequence and "use" it to initiate program action. If the program structure is coherent and (5) , processing procedures produce intelligible and useful results.

4（）

A．to determine

B．determing

C．determined

D．determine

肺通气的原动力来自

A．肺的舒缩运动

B．肺的弹性回缩

C．呼吸肌的舒缩

D．胸内负压的周期性变化

E．肺内压和胸内压之差