区位要素对区域选择的标准是什么？

A. 加味修肝散
B. 将军定痛丸
C. 石决明散
D. 清气化痰丸
E. 平肝清火汤

A. 截止频率
B. 特征频率
C. 最高频率

A. decreasing the amount of valve overlap
B. preheating the air intake
C. after-cooling the intake air
D. preheating light fuel