13.下列何者屬於呼吸器的氣流控制閥（flow control valve）？ ①proportional solenoid valves ②mushroom balloon valves ③stepper motors with valves ④digital valves with on/off configurations
(A)①②③④
(B)僅②③④
(C)僅①③④
(D)僅①②④

Mushroom balloon val...