A client hospitalized with pneumonia has thick, tenacious secretions. To help liquefy these secretions, the nurse should

A. turn the client every 2 hours.
B. elevate the head of the bed 30 degrees.
C. encourage increased fluid intake.
D. maintain a cool room temperatur

袋收尘器开机时，应先接通压缩空气至储气罐，接通控制电源，启动排灰装置；（）